As I say, or as the Cardinal Vicar of Rome said, "which by order of the Holy Father all are required to give ear."? I am amazed you dispute that. It would take some pretty serious conspiracy facts (not theories) to refuse this as being Pope St Pius X's directive. It doesn't sound to me like he is inviting us to follow his liturgical reform if it does not offend our sensibilities, but rather, that he is restoring divine worship according to the will of Holy Mother Church. That the whole assembly of the faithful should join in the singing is the very first rule he lays down after stating that this is by order of the Holy Father. Let the scholars do their work. But let us continue to worship in the way that has been handed down to us until a more competent ecclesiastical authority determines otherwise. Or else we will have nothing but confusion and disunity in the Church. There is enough of that already.

OK, while what St. Pius X had in mind perhaps reflected some kind of ideal, in practice, it was a mistake to promote it and a disaster.  OK, MAYBE in Italy, where singing is so much a part of the culture that people learned how to sing before they could even talk ... but in 99.99% of situations, it's an unmitigated disaster.  Obviously this is from the 20/20 hindsight of what happened later, and also from a practical (vs. theoretical) standpoint.

Yes, I found it edifying to participate in the chant, especially the psalms and Divine Office at STAS, but in every other place where I found myself surrounded by congregational singing, it was an unmitigated disaster, with 3/4 of the congregation either mispronouncing or even badly butchering the Latin, and even a greater percentage unable to sing on key if their lives depended on it.  Some believed themselves to be Pavarotti reincarnated and belted stuff out an extreme high volumes (and many of these types mispronounced Latin and/or got the words wrong and/or were off key), drowning out many of the at-least-adequate singers around them.  In every case, it was headache-incuding, distracting, disedifying, and did harm to the dignity of the Mass.  Even St. Pius X stated that it would be better to have Low Mass than to have Sung Mass done BADLY, and I've never experienced it NOT done badly outside of STAS.  If someone tried to pull that nonsense at STAS, where they sang really loud, off key, were butchering the Latin, they'd be pulled aside and told to stop, to keep it very quiet until they could figure it out and learn how to do it correctly.

In addition, while hindsight is 20/20 and St. Pius X didn't anticipate the coming Liturgical revolution, it was a mistake to promote some notion that the ideal fo the Mass entailed "active" participation from the faithful, rather than primarily spiritual participation.  That's precisely the attitude that led inexorably to the Novus Ordo.  As one of the articles points out earlier in this thread, the translators of the Latin snuck in the adjective "active" for "active participation" that nowhere appears in the original Latin, exploiting this for later gain.

This is similar to other papal mistakes, such as when Pope Leo XIII in Providentissimus Deus made some ill-advised statemets that, when properly interpreted were correct, but then gave an opening for the Modernists to go to town on it to absolutely undermine Sacred Scripture.  Or when Pius IX made some statements about EENS that were technically correct, but which the EENS-haters went to town on, distorting and misinterpreting it to undermine EENS dogma.  Pius IX himself was surprised and angry about the prevailing (mis)interpretation, but he made a mistake in not realizing that this would happen.  Pius XII did LOTS of stuff that were highly regrettable that led to disasters, such as allowing discussion of evolution, opening the door to NFP as Catholic birth control, setting up Bugnini to start the liturgical experimentation, permitting various experimental Masses, such as the "Mass of the Future", permitting Catholics to participate in the first Ecuмenical gatherings, and on and on and on.

So, not only was this an ill-advised step toward the notion of "active [physical vs. spiritual] participation" being essential to or ideal for the Liturgy, but congregational singing is fraught with the danger of not being distinguished from the purely liturgical parts of the Mass that are inherently intended for CLERICS to execute, taking a step towards the whole notion of "lay ministers", where the roles in the Mass were merely different "parts" rather than as public prayer of the Church that were extensions of the priesthood (formerly requiring Minor Orders as a result), leading ultimately and inexorably to this notion of the "priesthood of the faithful".

So, maybe in Heaven, or in an ideal state ... to some extent (without blurring the distinction between the faithful and the clergy), but in practice an unmitigated disaster that the Modernists would also exploit to completely undermine Catholic theology regarding the Liturgy.

On the contrary, what better way to attend Holy Mass than with the very words Holy Mother Church uses? I am no newcomer, and this is certainly my preferred method to pray the Mass.

That's not to say there are not other ways of attending Mass as you rightly suggest. I derived great profit in my younger years from reading St Leonard of Port Maurice's Hidden Treasure, Holy Mass which gives a method of assisting at Mass whereby we divide it into four parts, each dedicated to one of the four ends of the Mass/prayer i.e. adoration, thanksgiving, reparation and supplication. However, the very prayers of the Mass fulfill this same purpose, obviously.

This is a quote taken from a 1953 pastoral letter of Bishop de Castro Mayer: "Mediator Dei insists upon union with the intentions of Christ our Lord and that of the celebrant, and leaves it entirely up to the faithful how to realize this end... All exclusivity in this matter is reproachable."

I do recall one SSPX priest having to interrupt his Mass and turn around to address the choir: "Would the schola please stop singing"!

Of course, I find that a bit uncharitable (and have seen priests do similar) to do it during the Mass.  I would just very quietly and kindly take it up outside the Mass.  This would be very humiliating to the poor souls in the choir who were undoubtedly trying their best.

Also moms giving off a somewhat charismatic vibe.