I think they lost against (or gave up) fighting spam somewhat around 2010 so they really don't have any modern experience on page reliability anymore. Presumably they thought that they didn't need to care as they got their money from paid top results and had an enormous market share.
All the engineers of the golden days are gone and the web changed so much from back then that I don't think they really have a leverage in this area anymore.
Google stopped fighting spam when they realized paid ads made more money than organic relevance
Yeah that's also my analysis, they got paid regardless of the results so why would they care? If anything, better results would cost more and eat the bottom line.
Now we're 15 years later and suddenly quality matters again as the competition is fierce in the LLM world. However they have been out for so long that they lost their edge.