On some airports there’s no ATC. As in, you would go and open up the ATC window, request IFR clearance, there’s no audible (or written) response and after some seconds, they would request you to acknowledge the last transmission.
You acknowledge it and that’s it: no more interaction from ATC until you take off and reach some other zone.
This is game-breaking, since you are unable to even pushback. And it’'s annoying when you try to play realistic and input all your data on the FMC while the plane starts up just to discover that your flight cannot even start because you can´t go to the runway.