When this came up in the context of Bitcoin, my back-of-the-envelope calculations were that Bitcoin and US spam paper mail were roughly the same order of magnit

When this came up in the context of Bitcoin, my back-of-the-envelope calculations were that Bitcoin and US spam paper mail were roughly the same order of magnitude, close enough that I couldn't say which was actually bigger with the error bars on my envelope. Ban enough things like that and soon you're talking real impact.