My understanding is that GOG is not necessarily undesirable, but they are very selective: Unlike Steam or Itch, you have to convince them that it's worth their while to sell your game. And their choices of what (not) to sell are not infrequently baffling. Lots of developers have gotten burned by that, including Zachtronics
The Turing Complete dev was pretty unhappy with them and ended up leaving again despite having been accepted and making it onto the GOG store.
I have a hard time believing that GOG rejected a Zachtronics game. They're popular, high quality, and a good match for the GOG audience. An GOG already sells several of them (I own SHENZHEN I/O and Spacechem on GOG).