Just like nobody can _stop_ you from murdering another person or demanding a bribe or any number of terrible things.
I don't understand the point of your vehement sophistry. Everyone understands how societies work. There are laws. People get punished after the fact for transgressing them. Cryptocurrency is not somehow magically exempt from that reality.
The person you replied to said that cryptocurrencies are illegal where they are. You said nobody can stop you from accepting cryptocurrencies. Just like nobody can stop you from doing any other illegal thing, like not paying your taxes or taking drugs. Sure, you can do these things and you may even get away with it, but if you get caught, you get fines or jail time or whatnot. If cryptocurrencies are illegal where the person you responded to is, sure they technically can accept cryptocurrencies, but if they get caught, its no different than getting caught doing any other illegal activity. You might say "well, its hard to get caught!" but you could say the same thing about laundering money, evading taxes or buying drugs, yet people get caught doing these things all the time.
I don't understand the point of your vehement sophistry. Everyone understands how societies work. There are laws. People get punished after the fact for transgressing them. Cryptocurrency is not somehow magically exempt from that reality.