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.