As someone that's been watching the process fairly closely, that's not my read on the situation. I think it's moreso just a new technology that takes time to perfect, and Ethereum is a large ship, hence "changing course" take a lot of effort.
In an Ethereum echochamber it may seem like that. More generally on 'why hasnt it taken over?' a lot of projects have communities that laugh at the security properties of PoS; they will never consider it
