Most tech calling itself web3 has less privacy - rather than 'just' Google knowing who I am across the internet, I'm spreading correlating information and pointers to publicly accessible records everywhere.
Privacy isn't some technology you can add to the stack. Rather than adding ZKP sprinkles on top, every technical choice will ultimately need to be reevaluated if privacy is a goal. Basically, you're talking about web4/5.
Potential of paying for services and being able to require privacy in return? It is not a choice one can make with many web2 services (e.g. google).
As for "blockchains are transparent and can't offer no privacy" - just a question of time. Tech is already here (zkps, mpc, etc).