I enjoyed reading your post, but I think that what you've mostly addressed with it is why it's not possible (in practice) and not why it's not encouraged (the point of the OP).
I intentionally worded it like that, because I already addressed why its not encouraged in my first reply (i.e. the protocol becomes the least common demoninator, which is exactly what the protocol architects do not want).
Having the protocol be the least common denominator is
exactly what the protocol architects should be striving for. Everything else is an implementation detail. To keep things truly decentralized the knowledge of how Bitcoin works should be spec driven. This allows every technical person to weigh in on the high level challenges of the protocol through documents like bips. A friendly environment towards more implementations also helps ensure a system of checks and balances where core devs can't dictate the direction of the protocol against the majority of user wishes just because they have market share.
A real-world case study of this approach can be showcased through web browsers. Sure most browsers are based on chromium but browsers like Safari and Firefox (and spin-offs like the Tor browser) have unique approaches to protocol implementations that many internet users value.
That's very well put, and exactly how I feel. Have a merit and welcome to the forum!