If we start counting all useless tokens in crypto space you will notice that most of this useless tokens are running on erc20 block chain ,many good altcoins ive came across have separate owned block chain and they are plain better, I guess the reason we have too many shit altcoins in crypto space is because of the flexibility of erc20 ,making it easy for unprofessionals to build there useless tokens.
We have some good altcoins that are running on erc20 but you will see then moving to their own block chain later on or it will be included in their roadmap about the future swap.
The reason why I like tron block chain is the ability to get rid of fake tokens running on tron blockchain if ethereum can do this it will help a lot.
My answer is too many shitcoins are based on erc20.
Maybe 90% of these scam projects are on ERC20 all the bounty that I've participated in are all almost on ERC20, because it is easy to maintain it's like set and go no need to do anything, we have a ready explorer and decentralized exchange for it, really make things easy for scammers to create one.