This is why, instead of debating about whether or not games are railroads, it seems more helpful to talk about what sorts of authority the GM exercises over the shared fiction in different sorts of games.Honestly I think the popularity of D&D has something to do with this.
The DM can always just throw in a fight and by the time it's done it's time for everyone to go home and the DM has a week to think of what to do next.
And more generally I think a lot of players find role-playing in character mentally taxing and a fight can be a welcome relief.
If - for the reasons you've said - we want the GM to be the one who mostly decides what happens next, and/or we want player decision-making to be confined mostly to declaring actions in combat, then lets be up front about that, and talk about how to do it well.
Again, this doesn't seem like something I would enjoy but is a type of play I've witnessed, and been a player in, back when I played in a club. It makes sense to talk about how it works. And why, for instance, do we still have die rolls in combat? (I think the answer is something to do with setting up tension and releasing it - it's a pacing device, not really a resolution device, in the sort of play you're describing.)I wonder if there is a non-osr version of "story after," where the goal for the dm is to consider whether anything that happens at the table will make for a good story later, whether or not it is prepared or random. So, you roll on the random encounter table (in part because this is a vestigial aspect of the game in 5e), and if the result seems either boring in the moment or not something that will produce a good story later, you ignore it. If a monster rolls a critical that would kill a pc, but that wouldn't be the right narrative moment for that pc to die, you ignore it and fudge the result. I could see the appeal of this kind of thing, as the role of the dm would basically be to ensure good pacing, especially when you have limited time to play, though I still think a more emergent style is more fun.