Child pornography in any form should be banned, including to those individuals that use bitcoin as a tool to promote this. This is totally unacceptable and should be stopped.
I agree, any criminal offender can use any currency, not just bitcoin and crypto. Most of them often even use usd and fiat money because it may seem easy for them to handle and start faster transactions for their clients. However, bitcoin has recently been accepted on most porn sites and apart from credit cards and I think it's much easier for them to use than to give cards that expose their true identity.
And it depends on the person's person and how they will use the money / currency. So it's not a full btc or cyrptos error. Even cyrptos exists or not, such crimes will still exist.