At this point the reason governments are not cracking down as much as they could is increasingly not just that that would do quite a bit of damage among e.g. VCs and institutional investors (think pensions). People come out with pitch forks if you start messing with their pensions; so that is a big reason to maybe talk tough but let it happen at the same time.

But there's also the FOMO factor. Governments are afraid of missing out and getting run over by e.g. the Chinese doing this regardless of what they allow or won't allow. In the US particularly, this is a direct threat to the relevance of the dollar as a means to conduct international trade. For the same reason China is moving pretty aggressively against certain crypto currencies while openly backing and endorsing others and e.g. the Chines national bank openly flirting with moving their currency on a block chain.

That's why a lot of this stuff is happening under the watchful eye of the SEC with companies head quartered in San Francisco.