The exact opposite happened, contrary to this often repeated meme. Both SO and Wikipedia became what they were because of their strict moderation and RTFM-implied attitude. It's what drove professionals like me to the site. I'm just a regular user BTW, but it felt like SO people were my peers.
But SO (the company) wanted it to be more accessible, easier for newbies, "nicer", there was a huge uproar over them publicly blasting a moderator over a disagreement on a unilaterally imposed new code of conduct, and recently they even (again unilaterally) effectively reverted the ban on LLM-generated content. This has been going on for years, and moderators have less power than they ever had. Imho this whole thing started much earlier, I think it was 2017 when they tried the SO documentation project and let everyone keep their rep where I first thought they had jumped the shark.
The company has been on a bender for the last few years, and high-ish rep users like me just don't see the value in answering anymore. With recent blog posts it seems even more clear that they are on the direct path to enshittification, against their own actual users and moderators.
Recently it feels like all the actual professionals have left and what remains are "students" asking low effort questions in bad faith while an army of spambots tries to pounce on these.
While this means boosted engagement numbers short-term, it spells death of the site long-term. SO cannot survive on low quality spam, even if other sites (like Reddit) may be able to.