But I expect someone will be along shortly to "correct" my understanding.
As a neutral (I own no bitcoin), the whole thing is very dogmatic, very messy and looks like it's about control not about the limit at all. In fact many core devs were previously arguing for increasing the limit until it became clear that that position wasn't compatible with their position in core.
Outsiders see core as having been corrupted by the wishes of blockstream VC money. Pro-core see all outsiders as a conspiracy trying to wrestle control away.
In short, it's a complete mess.
There are already competing implementations like btcd written in Go. That's not the issue.
This post is from a developer who is part of a small group in the bitcoin world, who want to change the rules of the protocol. Anyone that did not follow those rule changes would see a different ledger.
That's not something that should be done in bitcoin - changes this big should be very hard to pull off, and require consensus of all parties. Most are strongly against these changes because it does not really do much, makes the network more centralized, and mainly because there are much better options to reach the same goal (that are being worked on right now).