Fun fact: in the long list of new gen 7 abilities, with the exception of Beast Boost, only 1 of them wasn't exclusively given to one Pokemon (Slush Rush).

I find this is potentially a bad trend. Instead of new abilities being flexible, they're basically just part of a certain Pokemon's design. Several Pokemon even have only 1 possible ability. XY had its fair share of exclusive abilities too, but still had some that were distributed to multiple others, like Tough Claws and Competitive.