Profile of Hannibal

Pioneer are SMG troops that can not attack past initial fighting and their best combat use is defending HMG from flanks, while having to fulfill a number of other roles including building base building.

From my experience it is rather rare to see a vet 3 pioneer.

Pioneers can decently vet up if they have a flame thrower, however usually only the ones that have been built early.

But my point was not about about pioneer veterancy. My point is that pioneers compare decently against enemy units at the start of the game. This dynamic does not change until the enemy units either get upgrades or combat bonusses from veterancy. And since vet1 is usually reserved for utility, vet2 is the first point at which the actual combat performance of pioneer vs XYZ is changed and pioneers become less effective.
Squads do not reach vet2 nor weapon upgrades within 2 minutes, that's why I said your point that they are "not useful in combat past minute 1" is an exaggeration. Pioneers are usable in combat for the first 5-10 minutes depending on various factors. Only afterwards they fall off.

OP seem to have trouble dealing with hmg and that has probably more to do with refusal to build mortars than the performance of RE.

Cost of RE is really irrelevant in what he describes as the issue since the unit comes for free.

Rear Echelons cost 200 MP, they are not "free".
His OP was about a comparison with pioneers. If that makes sense is another question, but Echelons are without a doubt the worst early game unit. Vanilla they are similar to Combat Engineers, but those at least get better utility, a flame thrower and are both cheaper in purchase and reinforcement.

I also don't think RE are initially worth their 200 MP cost. They are probably the least useful unit in the early game having both bad DPS and little utility. Since USF has crew repairs, they are one of the very few units I do not rebuilt until I really need the sweeper.

I agree with the points that others made: Weapon racks (or better to say bazookas) make them decently efficient. The issue here is obviously that those weapons have to be priced to fit basically any unit of the whole USF faction. So making REs cheaper could result in bazooka/BAR spam tactics, which in turn could only be fixed by increasing the price of the weapon racks and/or weapons themselves. Which then again would affect Riflemen as well.

Since REs are not really needed for USF to work, sacrificing their early game usefulness is the easier (and smarter) choice.

Thank you for the answers. I'm aware of this elevation, covers, etc.

This is just one unit very exceptional and dodging hits even though its parked raketeen and P4s (very close both stopped) are unable to hit it.

I'm guessing there's a buff on it size when it hits veterancy? it's almost invincible in vet3 with its speed, acceleration, and sight.

Most of this as Klement Pikhtura said is just skewed perception. Everyone remembers the times they got screwed over by the game, but not the times you got lucky. Most of the shots of that any unit in the game fires do hit the target, so the base expectation is to get at least a hit. That's why misses are much more memorable.

The T70 gets only mobility buffs regarding survivability. The reason why it may seem invincible at high vet is because of the high sight radius in recon mode and good mobility of the unit, making it hard to catch against even mediocre players like me. If it actually gets in range of Axis weaponry, it is not more survivable than other light vehicles.

Not that I could speak of top tournament level play from experience, but my two cents:

First, we mostly saw especially USF and UKF in tournaments when they had one single strategy for rushing. Either the Jeep/Cav rifle or the UC into AEC combo.
Second, I somehow have the feeling that balancing has shifted a bit away from focusing on 1v1 like the first patches did to rather 2v2 and 3v3. This allowed removing or at least toning down some of the "gimmicks" that made those factions strong to compensate the gaps in their line up. But this might be just a confuse feeling since I can't really think of specific examples. However, I am under the impression that the removal of gimmicks coupled with still having glaring gaps in line up lead to DLC factions being overall worse in 1v1. They were always predictable, but now their predictable path is not as strong anymore. In team games, missing units can be compensated by team mates so they are not AS serious as in 1v1. You can still focus fully on your faction's strengths. I can also imagine that the "one dimensional" design of UKF/USF/OKW leads to very clear counters. You only have 1-2 strategies that you can play, and if you have a good opponent he will know how to give you a hard time.

Lastly, there might be a psychological factor: Soviets and Ostheer are the safest bets because they do not lack any tools. Knowing to have all options at hand relieves pressure when you can actually win something. Why take options away from yourself when you actually don't have that much benefit from it?