Your statement is provably untrue because all the PoW alts represent forks of Bitcoin which started with very small userbases and grew.
PoW alts are not bitcoin forks..
a bitcoin fork contains the last 4.5 years of bitcoin transaction history, that then takes a different path compared to another.
the other PoW alts DO NOT contain bitcoins history, thus they are not forks. but simply mutated code .. they have nothing to do with bitcoins blockchain and again have nothing to do with 'forks'
you could call them spoons.. meaning the handles look similar and the purpose is similar but they are not the same thing. they were made separately