This is a narrative that MS, Google etc want you to believe. They gutted it for ads. That's what's happening. There are workarounds now, that's what the existing ad block options are. They are heavily kneecapped.

MV3 is severely limited in what it can do. One example that blew my mind is that chrome happily renders webpages immediately after application launch, while extensions are still loading.

Firefox, in contrast, doesn't let the network request fire off to the page until every extension is ready. So chrome is essentially screwing over the user, letting ads/ blocked content load, and intentionally degrading their experience, to make things appear slightly faster.