Creating a working implementation of an algorithm like Chacha20 is really not that hard if you're comfortable with bit twiddling. It's much harder to create an implementation that works and doesn't have hidden problems, like being vulnerable to timing attacks. So they've made it slightly easier to do the easier part of crypto (get a correct result), while increasing their attack surface and the amount of effort that it takes to do the hard part of crypto (getting a result securely).