Ad revenue from increased user count, spying on browsing habits, scraping user-input data, and promotion-hunting by product managers who want to advertise how their new feature led to X million more clicks per day.
I assume every website I look at on Chrome is sent to Google, I don't see Microsoft not doing the same. But the thing Google has and Microsoft wants is to be in full control of web standards.
You can't think of Microsoft, or any company, as a monolith or personify them. The question is not how Microsoft benefits from this but rather which executive benefits from this. Given that I believe Windows team is now grouped together with the Bing (and Edge) team, I think the reasons for these sorts of changes are obvious.
If you think it's so obvious, why don't you provide the answer? I don't think GP would have posted the question if it were obvious to them.
Whether you talk about Microsoft-the-firm or Microsoft-the-shareholders when asking about "what's in it for them": that's the same thing because it's a for-profit business, so that's an irrelevant thing to post as well.
I think the point (which I agree with) is this doesn't benefit Microsoft at all. It benefits a VP by them being able to show some metric move from Q to Q, and get a fat bonus. They couldn't care less about the long term effect on Microsoft's PR / reputation (they'll likely skitter off after collecting a few of those bonuses either rest&vest with some D&I initiative, or move off to the next victim to suck from).