The biggest objections to othismos dissapear when you accept my definition of othismos only occuring at crowd-like densities and understand how crowds push:
"Battles were long, men can't push that long."
The crowd cannot do anything fast. As soon as it starts to advance it begins to lose cohesion. Once this occurs it cannot transfer force through the ranks effectively. That is not to say "pushing" stops, but by my definition, the type of pushing done by the first few ranks with not transfer of force from deep in the file is not true "othismos", but the same shield bashing and pushing seen in a clash of any group of close-in fighters such as during Roman battles. For the most part in the Crowd-Othismos men are simply standing and leaning. It is exhausting, perhaps moreso mentally than physically, but no more than active weapons duelling. The phalanx does not advance like a steam roller, but like a ratchet, with perdiodic loosening and tightening of the ranks. When a rapid advance does occur, like it must have as one side gave way, it was only the front ranks pushing and even they were doing more "herding" like we see with riot police and crowds, than pushing in the sense of othismos.
An advance in true othismos can only occur through shuffling steps until one side gives way. As they begin to rout, they reduce the pressure on their foes that the othismos-crowd requires.
"Men can't fight and push"
When authors envisioned men bent over like rugby scrummers I could understand this objection. In the Crowd-Othismos, men are standing upright, and but for the extreme close range, their right arms are free to do whatever they wish with them. Obviously at this range you cannot use your dory against the man ahead of you, but the dory is some 8' long, not an Iklwa. It could not be used at any range approaching shield on shield contact. Swords, broken spears, fists, foot-stomps/hooks and teeth would be the order of the day.
"Twelve ranks of Spartans could not resist 50 ranks of Thebans for more than a few moments and yet we know that this phase of battle lasted for some time, with the Spartans even gaining ground to pick up their fallen King."
Not a problem when we understand that coordination of the crowds movements is what adds force in the othismos. There is only so much coordination you can get out of a file of 50 men. Even with a deep phalanx you probably can't get much more than 8-12 ranks perfectly coordinated. Thus, each side produces a forward thrust of about the same size at any given moment. As we wrote above, the depth acts like a wall behind your back. If you are pushed back, it forces all your ranks to tighten and become de facto coordinated to resist being moved. Twelve ranks of Spartans could push back the Thebans, but at a great disadvantage. The figurative "uphill battle" could only end one way.
I'll note that my distinction of pushing at different densities, with othimos only occurring at the tightest packed is not something that the Greeks would have made. They only speak of battles coming down to pushing, they did not disect the process and probably did not undertand it any better than a college kid rushing a stage at a rock concert. To them the whole process was one event.