Nothing

LOL.

1. No. What you think is the case and what's really the case are very different things. Sure, some definitions in web3 might make it sound like you might get away with something but it doesn't make it so.

2. This has been thoroughly debunked. There's not even an indirect link between having to stay in an environmental nment and the efficiency of their services. In fact there's a good chance the opposite is true (untested yet): while privacy comes by default, web3 also comes with a degree of interop meaning that Google could use it's ML on Facebook data. Also, simply providing a clear choice to consumers makes up for any side effect.

3. Actually yes, you can know. The fact that there is data available doesn't mean there's 100% no tracing.

4. Based on what?

5. The opposite is true. Now you have to rely on centralised data stores to be even willing to correctly identify bad behavior and Facebook/Google et al have proven they simply don't want to invest in preventing or even identifying bad behavior (or abuses). Decentralization will allow more ways of people willing to fill in the gap, so it's very possible that there will be less bad behavior overall.

Have you ever heard about the "Stockholm Syndrome"? 🤪

I know or understand very little about blockchain or Web 3.0, but even I intuitively suspect (no, KNOW) that this article is the product of confused thinking and completely misses the mark.