Parmandur
Book-Friend, he/him
I am defending nothing. I did note a bit that you were trying to teach a grandmother to suck eggs, but that is less being defensive, and more, "Dude, you're gamer'splaining."
Um, not quite.
5e has a unified mechanic, but "unified" is not the same as "generalized". 5e is still pretty much a list of approved actions, it is just those approved actions all have similar mechanics for determining success - rolling a d20 and adding some stuff.
What keeps it from being generalized is that while the thing you need to do to determine success is common, there is no common framework for what success actually does.
I noted a fine example, which you promptly ignored - sand in the eyes.
In 1e... whatever the GM says.
In 5e, I can expect I will need to roll a d20, and add some stuff. Unless instead the target is making a save, in which case they are rolling a d20 and adding some stuff. There are several options of what determines the DC - the GM gets to pick. And as for the result: Maybe it is hit points of damage. Maybe it is disadvantage on some roll. Maybe it is some level of concealment. It is... whatever the GM says.
I am not convinced that "unified mechanic" is really helping all that much over 1e, in terms of "freeform action".
Well, it allows action in a free-form manner, with improvisation by the DM and players. Not reinventing the wheel every time, but not hampered by rules, either.