> Bitcoin Cash is the only 'true' fork that survived beyond the splitting of the BTC chain

This seems like a "No True Scotsman" fallacy and isn't correct unless you take liberties with the concept of "true fork" or you are making an observation about the lack of mass-scale adoption of the smaller forks.

Every protocol change in Bitcoin is in the most literal sense a "fork". There was a time at which the proposed protocol change might or might not survive the fork attempt. The community (developers, miners, holders, transactors, etc) all vote with their feet.