I am citing the actual history of the US public library system, which ironically can probably now be found only with difficulty in actual public libraries. But Wikipedia has a decent overview:

https://en.wikipedia.org/wiki/Public_libraries_in_North_Amer...

As you can see, libraries in the US were founded to advance 'learning' and 'piety'.

Here is the treatise of one of the biggest influencers and advocates for the creation of the public library system.

https://ia600909.us.archive.org/10/items/intellectualtorc00t...

I strongly encourage reading all the citations in the Wikipedia article surrounding the creation of the library system. Sadly, many of them are paywalled and inaccessible via even the Archive project, Google Books [ed - to be clear if you think I am pro-publisher, you are wrong: the former two projects had more potential to do good than I can express], and likely your local library. But you can find enough to prove the point.

There has been a massive shift in the mission of libraries in the past several decades, and the public didn't get a say.

You've failed to show how that 'shift' leads to them no longer serving that function. Besides elitist "they now provide things I don't deem to be of a certain quality" that is. Your post just falls into a long list of "things were better in the past" rants. All of them bullshit.

Some things really were better. Some things were not. I’m not sure why you would throw all such complaints into the BS category. Why is that?

The mass destruction of older books and classics is easy to observe by searching your own library catalogue. I provided some sources and one commenter even provided a link where librarians justify the need to destroy books using outdated or biased language.