As I said elsewhere, "the indefectibility of the Church requires a hierarchy with the power of jurisdiction or rule/governance, which means legislative, judicial, coercive, and administrative power - the power to make laws, mandate liturgical and sacramental norms and rules, make binding discipline, and the power to punish those who violate the laws, rules, etc."
Of course, I passed over initially what a joke this statement is. So let's see, this hierarchy has to have power to rule and govern, to legislate, coerce, mandate liturgical and sacramental norms and rules, make binding discipline, and have the power to punish ... except when you decide that you don't like said rules, mandates, legislation, coercion, discipline, liturgical/sacramental norms, etc.
So basically the "authority" you grant (and it is you who grant it, since you're also at liberty to take it away) to this hierarchy is utterly meaningless and consists of nothing more than lip-service, since they have no authority in any meaningful way, if you decide that these laws, mandates, and liturgical norms don't conform to your perception of being good or Catholic.
In other words, you grant them no real authority and are "preserving" absolutely nothing, but gutting the "authority" you grant them of any real meaning or efficacy, i.e. you grant them a non-authority.
So what's the difference if they have an SV non-authority or an R&R non-authority? At least in the SV paradigm, when there is an actual legitimate pope, that pope has REAL ACTUAL AUTHORITY to do all those things you listed, not some mythical, made-up. lip-service authority that any Catholic can take or leave at his pleasure.
It is YOU AND YOUR ILK that undermine and reject the indefectibility of the Church, not the SVs, for if we do have a legitimate Pope and bishop subject to said pope, and they can wreck the faith with this authority and you are free to take or leave any act of their authority based on your own personal/private judgment ... then that authority is meaningless, and why do we even care if it exists? Oh, yeah, true, once or twice a century on average, they may say something with the notes of infallibility that you're required to accept, but the rest is fair game and up for grabs.
You set up a non-sensical and non-Catholic notion of papal authority, jurisdiction, and Magisterium that you claim SVs must also adhere to or otherwise THEY undermine the authority of the hierarchy? It's so pathetically laughable that you have to be pertinaciously dishonest to buy such excrement.