Tell that to Microsoft... didn't prevent them for banning thousands of users.
Banning, yes. There is a huge difference between banning a user from using an Online service that has a Terms of Use agreement that you agree to and rendering a physical device inoperable.
Banned XBox'es are still XBox'es - they still play games, they're just banned from using XBox Live because their user was in breach of the XBox Live contract. XBox Live is not a part of the XBox package, it's an entirely separate service with its own rules that you have to follow in order to use it. When you go into a store and you buy a consoles, you buy "goods", not "services" - those two are mutually exclusive.
Similarily the government isn't going to torch your car if you break the law severely while driving. They can take away your capacity to drive, meaning your license, but they won't destroy your car - your car is a possesion of yours, it's something that you legally own.
No bricking of systems will take place because it's illegal and infringes upon your personal property - Nintendo would be in a world of trouble if they resorted to that.