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The Universal Ordinary Magisterium is infallible always. That’s de fide, not bogus.

This is not in dispute.

What is in dispute is that your statement, which is truth, is being used to promote the error that the pope / hierarchy are themselves  the Ordinary, the Solemn,  and the Universal Magisterium, that these people are infallible [even] when they aren't, and that whatever the pope alone or in a council teaches, is by that account made a part of the magisterium - and this error is endlessly promoted in spite of both historical (V2 itself) and present (it's aftermath) reality, which reality must necessarily be entirely rejected and denied in order to consistently promote this error - in an erudite manner of course.

In a nutshell, they boil it down to either one has faith in and believes the above promoted error and on that account, rejects all things Catholic and is a devout NOer (as "the magisterium" teaches), or, they consistently prove that they have no faith whatsoever, by that I mean they indisputably prove that they have absolutely zero, zilch, nada faith in their own false idea of what the magisterium is, reject what the magisterium actually is, then profess one or more of the varieties of sedeism.  All this is, is iniquitous. All this false ideology proves is that it serves absolutely no purpose except to make people workers of iniquity as they strive, often at great length, to reject that which actually is de fide.

God often lets other fall into the same doctrinal and moral failings they unjustly accuse others of.

This.

Well, let's debate this question:  Which areas of the church are able to err?

Certainly not dogma, nor scripture, nor Tradition.  Also not the infallible magisterium, which explains dogma, scripture and tradition.  So the only piece which can err are the churchmen themselves, which are the ordinary, fallible magisterium.  Debating over which uncorruptible part is the rule of faith is an exercise I don't understand.  Scripture, Tradition, the infallible magisterium - they are ALL important and necessary pieces of the Church, without which, you would not have a Church at all.  Can we all agree on this?

The conclusion of this would be, since churchmen can err, and since the magisterium is dependent on churchmen, that this is the least necessary (in the short term) of all of the 3.  In the long term, it will always exist, so there's no debate on that.  But short term, the magisterium could be affected, therefore scripture/tradition are the most stable of the 3.