Would be quite OP, but I don't see how auras affecting teammates are remotely similar. You don't exactly let allies bypass the need to spend resources or queue time to research something on their own; you bring your Command Tank elsewhere far enough and your allies don't get the aura. That's kind of the same with being near units in general.
Are you implying that there are far too many things that promote teamplay? Because the "there are plenty of them" isn't justification to remove some. A proper justification is if they are toxic, don't actually promote teamplay, or produce undesirable effects. Obviously tour case is the third, being they are OP. I just don't agree.
More importantly, the ones you list are universal elements of teamwork more than passive bonuses that aura units are meant for.
I think you should elaborate on why you think they are OP at all in a large team context.
Most units that give aura based effects has the cons of a cost opportunity attached to them. You are giving up infantry field presence, tech, firepower, at the cost of utility. This means you are vulnerable but you gain a huge advantage when you use the unit/ability accordingly.
When you are playing teamgames, that cost opportunity and vulnerability dissolves.
Examples:
-Command PIV bonus is insane. A 2.5% health increased made the 1 man snipers OP. A 25% health increase (20% damage modifier) is huge.
640HP/4Hits goes to 800HP/5hits
800HP/5H > 1000HP/7H
960HP/6H > 1200HP/8H
1040HP/7 > 1300/9
1280HP/8 > 1600/10
-Damage modifiers are really strong. 35% for SU mark vehicle, 50% for both FHQ (on top of acc and rec acc bonus) and OKW mark vehicle are really insane.
-The UKF heroic charge is both cheap and insanely good (can't remember the bonus atm).
-Killing an OKW officer doesn't retreat allied units nearby.
Besides the aura from the command PIV, i don't neccesarily think they are OP broken but they tend to be the best option in several cases limiting the opportunity of other units/commanders.
Problem is what Relic has done in the past, is simple nerf the overperforming abilities rather than making a unified behaviour across the board (see limiting some offmaps so they can't be called inside the base, but leaving others to do so).