Ethereum, is the first blockchain that supports smart contracts. With smart contracts, it has been very easy, to create tokens, on the Ethereum blockchain. This helped scammers, a lot because, it made it easier, to scammers, to issue a token, because they only needed a smart contract programming. To create a new blockchain, with it's own coin, it's more difficult. It needs developers, and a network of miners. That's why most scam projects, issue ERC20 tokens, that rely on the Ethereum blockchain. Many people, do not understand, the difference, so they blame Ethereum. But Ethereum, is just the tool. Scam ICO projects, are the bad use of the tool.