It's forced if you start from the perspective of "General relativity describes reality", and obviously so if you look back at the inspiration for relativity, on

It's forced if you start from the perspective of "General relativity describes reality", and obviously so if you look back at the inspiration for relativity, one of which was "there is no way to differentiate between different free-falling rest frames from inside a box". Of course it's not always the most convenient model, and there are ones in which gravity is indeed a force — the Newtonian approximation, for example — but the starting point of this article is "Here's how reality works if GR describes reality".