How Drivechains affects scalability/privacy exactly?

I believe they don't provide anything but shitcoining on Bitcoin. But even if they would provide some minor improvements, they would also introduce complexity and possible vulnerabilities. That's why we need to be extreme careful and consider if they are worthy in long run.

Stablecoins and nfts are not necessary feature in L1 and not needed. They can be built on L2 if somebody really want them.