Not sure about "likely much cheaper". Those methods are either funded by VC money (for the case of early startups) or in the case of bigger companies, their other products that monetize you in other ways.
BTC is expensive to transfer, but other options like LTC are not. It takes a small fraction of a penny (in USD value).
But then how am I supposed to commit crimes!?
There are other ways to do crimes with USD.
At least with USD, when you gotta do it, you can do it.