They are at least a wonderful training ground for new ideas. Some of those ideas are incorporated into Bitcoin,
Training for ideas?
Maybe you know that Ethereum or Monero were not the first altcoins.
I'm not talking about that. I was talking about altcoins in general.
Also you are wrong about only BTC-ETH-XMR being accepted. There are other altcoins accepted here and there
I am not talking about acceptance. I meant
P2P payments. All 3 coins BTC-ETH-XMR , are most popular coins used for mentioned payments. (P2P)
Monero was not even the first cryptonote coin!
First cryptonote coin was Bytecoin. I said that monero is most popular coin used for private payments.