I do not think it is the SEO, but Google adapting to its less-technical userbase (people who search for "facebook" and click the first result).

It makes sense for this target audience to give broad results. They seem to be relying more on neural language models to accomplish this.

Google also surfaces more authoritative results than Bing, Google thus favors bigger commercial sites.

Google is suprisingly good on vague searches (for instance, describing a singer's appearance and song themes will return the name), but getting worse on "conspiracy"-type searches (you will not find many amateur sites discussing the high-class escort past of the First Lady, because these lack authority, all results focus instead on the massive fine for posting allegations).