what doesn’t get approved, now?

What doesn't get approved are the things which haven't spent enough money and obeisance to ritual to submit the requests properly, and probably a few things which are actively harmful.

I know that this is just the libertarian turn 

Yeah, I wish it were.  What it really means is that the magical thinking that "FDA approval" is what makes something a "good drug" gets a little more weight, and does nothing to reduce interference or make it cheaper to bring useful things to people who can benefit.

Three experts resign as FDA advisers over approval of Alzheimer’s drug

The approval and explanation riled advisory committee member Aaron Kesselheim, a professor at Harvard Medical School who is also director of the Program on Regulation, Therapeutics, and Law at Brigham and Women's Hospital. In a searing resignation letter sent to acting FDA Commissioner Janet Woodcock on Thursday, Kesselheim called the FDA’s decision "probably the worst drug approval decision in recent US history."

[...]

In resigning, he joins neurologists David Knopman of the Mayo Clinic in Minnesota and Joel Perlmutter of Washington University in St. Louis, both of whom also announced resignations this week.

There's one piece here that I don't understand. Why exactly do we expect doctors to prescribe this medication that doesn't work, thereby wasting resources? Is it a situation where we expect patients and patient representatives to demand the medication, due to being scientifically illiterate (or because they are doing Hanson-esque signalling that they care) and then doctor-shopping until they can get it? Or is there some kind of pay-per-treatment incentive that will make doctors want to prescribe it? Or something else?

On one hand, I think the FDA shouldn't be gatekeeping as much as it does. The ideal, I think, would be if they were reduced to an advisory role, where they published an opinion on which drugs are good, and that opinion had some influence on insurers' willingness to pay and doctors' willingness to prescribe, but had no legal force.

However, an Alzheimer's drug is one where, by definition, most of the relevant patient population can't evaluate the evidence themselves. So under a relaxing-standards interpretation, this is a very bad choice for where to relax the requirements first. And under the normal interpretation of what FDA approvals mean, this is just straight-up lying.

I have begun to think that the biggest factor in a drug being approved is drug company sponsorship, and thus the potential for drug company profits. Patentability appears to be a big factor. 

See "regulatory capture". 

Your first link (the one in the "This is a linkpost for ..." intro) is broken. I think it's probably meant to go to https://blogs.sciencemag.org/pipeline/archives/2021/06/08/the-aducanumab-approval .

The best steelman I've heard for the approval is that the FDA just created a multi-billion dollar market for Alzheimer drugs. Once people are paying 50k/year for this drug, other companies will have enormous incentives to try to get a piece of the market, which will create better treatments over the long run. So yes, right now there's gonna be a lot of money wasted on an ineffective treatment, but here the FDA might actually be incentivizing more innovation.