The problem will self correct
Once enough shitcoins have come out and all the gullible people have been scammed.
As for "holding back useful crypto", that assumes there is such a thing. Unless you're in need of a way to launder ill gotten gains, there's precious little use for cryptocurrency aside from speculation. If anything all the scams will make people concentrate on the two they've heard of and have been around a while, bitcoin and ethereum. Is there really a need for more cryptocurrencies? We've got those two, the rest are useless.