I totally get this. Back in the day when I was a kid, we went to the local library and read about the world. When the librarians weren’t serving me by “checking out books” to me, they were busily putting new and improved titles on the books in receiving. /s Seriously. Google is starting to feel less like the librarian of the net (we index the world) and more like the Truman show: we craft your reality.
1. Google doesn't care about the sites. The sites aren't Google's customer.
2. More importantly, the person doing the search is the customer.
Unfortunately, most sites believe SEO is about them. They can improve how they present themselves but the "transaction" is not about them.
Google, serving ads aside, needs to maximize customer satisfaction or run the risk of losing a customer.
It's worth repeating: Google doesn't care about rhe sites.
If Google believes a site's content is a good fit for maximizing customer satisfaction, but the title isn't optimal then it makes perfect sense Google would want to optimize the title, if the title is the "gateway" to a happy customer.
Whether that's right or wrong, IDK. Whether it actually helps, again IDK. But from a pure relationship / business perspective it makes sense.