Do you not see how that is a serious condemnation of the alleged "balance" in 5e? Like, for real. You are literally, straight-up saying that martial characters are gimped compared to non-martial characters. You are thus saying we should neither add nor replace anything that would improve it.
Unless, of course, you aren't actually saying that? The whole point of the thread, from the OP on, is that people are saying, "No. You cannot add a Warlord that would be above the power level of other martial classes. That is unacceptable because it would be broken." But clearly 5e can handle things FAR more powerful than the level of martial classes--because that's what literally everything else is judged by! So it's not "overpowered"--it's simply above the point that martial characters are forced to stay below.
So. Are you saying you accept that martial characters currently are held below a power limit that is neither necessary (since other classes exceed it handily) nor warranted (since nothing in the fundamental concept requires such a limit)? If so, you literally aren't who the OP was talking about; you're comfortable adding new things that are, in fact, more powerful than the existing 5.0 options so we can raise martial characters up.
But it sounds, to me, like your "Fighter 2.0" is expected to be simply a co-equal alternative choice to the existing Fighter. In which case, particularly in light of the point made above about effectively nixing the old Fighter by creating something stronger, so everyone would just choose the stronger thing, you require that this new Fighter be no more nor less powerful than the existing one. If this is true, then that goes right back into what the OP is talking about: because the new thing cannot be allowed to eclipse any of the old things, it would be "unbalanced" to make it more powerful....even though 5e's "balance" already allows many things far more powerful than what is being asked for.
I sincerely doubt that it actually achieves anything like a 5e translation of what a 4e Warlord can do. In much the same way that the PDK does not, even remotely, achieve such a translation into 5e mechanics. It would, of course, be quite distinct from the 4e Warlord, if only because spells inflicting saving throws are a thing in 5e. But given the number of times I've been told that anything as simple as "allow someone else to make an attack" is totally unacceptable? You'd have to sell me on it, not just reference it obliquely.