When you said, "Gravity is massively more powerful than expansion," combined with your doubt that accelerating expansion has become accepted within mainstream cosmological circles, it sounded like an argument that the expansion would one day slow and reverse. It sounds like that's not what you were trying to say.
Yes, that's not what I was trying to say.
Maybe one of the cosmology buffs will check in and help us out here, but for my part I question the validity of likening the expansion of the universe (which is only postulated to be due to the effects of dark energy, not verified) to a force and then comparing it with the force of gravity, but perhaps it's just a preference for a different explanatory model that's at work in my mind.
As I understand it, modelling gravity as a force is not quite accurate either, but both can be reasonably simplified to such - more precisely if you treat gravitational effects as curvature of spacetime, the expansion is modelled as a reverse curvature (if you treat expansion in the same way as the cosmological constant) and this can then be simplified to a force model. But, I'm neither a Physicist nor a Cosmologist, so I'm open to correction.