> It puts a literal price on abusing a service, but how do you
set that price?
Start with a nominal one and increase it until the spam problem goes away.
Create escape hatches for people who can't afford it, e.g. you can either pay/mine a couple dollars worth of cryptocurrency, or you can have someone who paid vouch for you (but then if either of you spam you both get banned), or you can do some rigorous identity verification which is inconvenient and compromises privacy but doesn't cost money, or (for smaller communities) you ask the admins to comp you and if you're known in the community from other sites then they do it etc.
> I mean, if someone implements it and tries to solve the usability issues involved I would be open to this future, but as it is now, cryptocurrency has disappointed me.
This doesn't seem like an insurmountable problem to solve. To give someone some cryptocurrency you can either send it directly (useful option for advanced or privacy-conscious users) or use a service and then it should be no different than using Paypal et al.
The real problem is the regulations are currently designed to make using it an unreasonable amount of paperwork:
> Some of them may be caused by regulation, but to be fair, I think at this point it's hard to blame governments for trying to regulate cryptocurrency exchanges.
There's a difference between regulating exchanges and regulating users. If you're holding millions of dollars in cryptocurrency then the government is reasonably going to expect you to file paperwork and pay taxes on gains etc. If you're only holding three and four digit dollar amounts worth then they should leave you alone and you shouldn't have to do anything.
In theory you can strike a reasonable balance here where the crypto scammers go to jail but Joe Average doesn't have to file any more tax paperwork to use Bitcoin Cash to buy a pack of gum than to pay in physical cash. We'll see what the new administration does with it.