Less about specifically hating Roll20, than the blatant engagement in anti-competetive practices and the monopolization of the industry in a push toward a vertically integrated monopoly.
Sort of like if Hasbro bought out the main book printer used by a bunch of TTRPGs so they have a vertical integration and can basically force all those other games to either deal with a hostile competitor to get books printed at unsustainable prices or completely upend a huge section of their development pipelines, try to find another printer, build that relationship, rework the pipeline and formatting guides so the printer actually can print the books. That's a process that could take multiple years and millions of dollars to do. Both of which options would kill even large rpg studios.