The government.
I wouldn't blame the government for this. Businesses are perfectly capable of accepting crypto if they so desired and payment processors like bitpay do exist. What I would argue is that merchants are just not interested in doing it, or at least not most of them.
There have been some governments who have banned crypto if i'm not mistaken, but it currently is not a systemic problem. In the US, there is a local restaurant that I know of that accepts bitcoin and the government has no problem with this. The truth is that its a pain in the ass for the business. They're used to cash and credit cards and those methods are fast and easy.
Also if bitcoin hasn't gained a foothold, do you really think altcoins are going to? I would argue that a good percentage of the world population doesn't even know ETH exists and they certainly don't know that coins like WAVES or LTC exist. Though I don't want it to be this way, the fact is that people are comfortable with banks and cash and plastic money. Those things are ubiquitous and crypto is not.