Paytm incident is completely on Paytm. Compliance isn't to be played around with. They fucked around and found out.
Indians don't have the safety net of economic power (like the US does) to withstand huge instabilities. RBI being prudent helps and they've been doing a fantastic job of maintaining economic stability.
Do any of the companies gain (directly) from gaining UPI marketshare? No, they make little to no money on UPI. Even more reason to not hand over the power to one or two players. Imagine phonepe and GPay collude to charge transaction charges?