you miss something. Balancing means nearly equal dmg for all classes and not 5 op breaking classes. Bcs If classes are broken op, ppl will only play these classes and then we are back to gorge times.
The one-dimensional aspect, named damage, you propose being the axis with which balance is measured around leads to a variety of issues down the line:
1) How even do you measure damage on a broad, server wide scale? Damage is dependent on many conditions - gear, cards, cenedrils, ping, critluck, supports... This variable is incredibly unstable.
2) If damage is the only metric, how do support-capabilities fare into this? r/ch is arguably one of the stronger classes while also bringing quite the hefty buff to the party.
3) What about tankiness? Take HOTO for example: Champions are practicaly unable to die in there, thanks to their three defensive setskills and generally high defense even in demolishion-mode. Should they get nerfed over this?
4) What about difficulty of play? Again, some classes are much easier than others - why would anyone play a harder class without getting any benefit out of it?
Answer: Balancing is not just about creating equal damage for all classes, as then the meta will simply shift into more support-focussed folds. If those are evened out, players will gravitate towards the easier classes, as they are much more consistent to play. If that gets evened out, players will go for the safest classes.
Balancing could therefore be described as a plane on a graph; The axis have barriers to entry at which point a class will be viable for that role. The axis are damage, tankiness, utility and difficulty. The Integral of this function describes the class strength; the barrier to entry describe the roles a class can fill. If one attribute at one class spikes out too much in comparison to others, this class will be the new meta - no questions there.
This is a very mathematical view on the whole balancing debate, but the pure chase for damage has left meta classes to be uninspired, bland and basically the same. Boring. They are boring. Perhaps this is why many endgame players find the game a bit lackluster these days. Most classes play the same and you just choose the strongest class to run. Heck, even the warden, one of the most unique classes in concept has become bland as all hell, as now literally anyone and their grandma can run around with a pet.
And why nerf instead of Push: if you always push classes, you can solo dps everything soon without any supp in group and this will destroy group play, bcs ppl running with 4 ppl rofl instead of 10, if it's possible
Pretty much this. Nerfs are important, though buffing feels much better to the player.
To be perfectly candid, I think the methodology used to go about balancing wasn't/isn't the best in many ways; The frequency of balance changes is too low and the impact of these changes is too high. Slowly buffing/nerfing classes that need it, basically microadjusting them into the position they need to be is in my opinion a much better (although more time consuming) approach.