It is hardly. Noise.cash is actually a centralized censorable platform which provides an easy way to send BCH tips. Those txs are normal txs w/o OP_RET and impossible to distinguish.
Instead, there is no way to prevent you to send any content to memo.cash. Because you can directly record your content to BCH chain by using memo protocol.
Also the number of noise.cash users would be interesting to know. I really think Memo should consider adopting the model of supplying free sats for tipping.
I think some of them are robots.
