Why would Mozilla hurt Firefox's market share in such an obvioud and drastic way? Do they not have anyone at their meetings that brings up obvious and uncomfortable risks?

I use DoH on Firefox and love it but man, I myself would block Firefox in a corporate network I help oversee if this is the default. Matter of fact, web proxies already list DoH resolvers as anonymizing sites.

Even if this involves some profit with cloudflare,this is strategically terrible for long term goals.