I agree, for the most part. We apparently disagree on the practical implications. Or perhaps you are just eliding all pragmatic considerations to continue the debate.
Core has a structural monopoly on consensus code. This is not an attack on core, it is an observation of reality. This is what happens when you yolo a prototype blockchain client into the world. The client is the protocol. Of course this monopoly is not enforced, bitcoin is volunteerism. It doesn't need to be enforced because the disincentive to run any other client is so strong.
Google doesn't 'enforce' their browser monopoly because they don't have to. They can achieve all their monopolistic aims with constant breaking changes. They disincentivize users from running alternative browsers to maintain their monopoly. Same situation as bitcoin, just without an evil corporation pulling the strings.
The disincentive to run nodes with alternative consensus code is a natural outcome of the design of blockchain-based cryptocurrencies. Again, this is not an attack on core, this is an observation of reality. Stop playing teams, bro. It's net negative.
> Core’s influence is earned
A dubious claim since there is no practical alternative. Regardless, they are unearning it, IMO.