The only real issue with this argument is that it applied just as much, if not more, to 3e, and yet relatively few people complain about high-level 3e/PF1e fights taking for-bloody-ever to resolve.
No, on this I 100% agree with you. I would even add that 3e was WAY WORSE then 4e at high level, because every little circumstance chance caused a recomputation of bonuses, and you kept forgetting about some of them, which then caused backtracks, etc. It was bloody awful, first with 3e, then with Pathfinder when it became as bloated. For me, it also comes from the fact that 4e was designed as very linear in particular because although you gained a few powers, you mostly replaced them, which led to much less inflation of complexity than with 3e where everything was additive and became geometrically more complex because of combinations.
And therefore, the frustration with 3e was that it was almost impossible to run high level games, but the frustration with 4e became that high level games did not feel that much different from low level ones. Yes, you did more damage to wider areas, but your fights were still constrained on an earth-bound grid, because 3D was challenging to resolve and took a bloody long time, and it was discouraging (and physically impossible) to shift battle maps.
It was not until 5e that we recaptured the feeling of AD&D, with almost total freedom in particular using TotM. It's better than AD&D because the rules, although fuzzy, are still tighter and not relying on tons of house rules. And compared to 3e, there is still an increase of combinations but the use of Adv/Dis cuts through the bloody modifiers recomputations and the simplification of foes makes the DM's job doable. Also, concentration / attunement makes the game not so dependent on buffs and permanent items. In the end, it makes the game not so absolutely epic as AD&D and 3e, but it's really manageable and it feels cool.
That said, I do agree that 4e could have been significantly tightened up in this department. It's a game that benefits a lot from having a VTT. If it had come out 2-3 years later, or had offered a really really robust VTT option (e.g. something to legitimately rival Roll20), a lot of the issues would have gone away. Doubly so if they'd made all PHB1 options free to use for "trial account" members or something like that.
If you are looking for tactical fights, all games benefit from a VTT. But on the other hand, especially now that the pandemic has gone, face-to-face gaming is way better than remote, and if you want to go fully epic, at least for us, TotM is the only real option, with possibly some scribbling to vaguely keep track of who is where, and it's hard to do with a VTT/
Apart from the VTT side of things though, using MM3/MV math, placing some reasonable limits on off-turn and reaction stuff, cutting out unnecessary dice rolls, and overall "streamlining" the process of play would have done a lot to improve the speed of play without meaningfully affecting the rich tactical experience.
This off-turn (almost complete) suppression is indeed one of the great advances of 5e, it means that we can go around the table in a flash without all the backtracking and the lengthy discussions, and it really allows us to run quick exciting fights at all levels without spending the whole evening on one. Yes, it's less tactical than 4e, but it's not what we are looking for anyway.
