[Shujin]

Since this is litterally not even benefitting anyone specificallyin gameplay or RP in those cases, I see little issue aswell.

It's basically just another storytelling tool, and making it a bit more fun using the gameplay mechanics that are actually quite enjoyable when not abused in a minmaxing way to "win".

As with many things, I feel aslong as there is consent on both sides and everyone is aware and agrees on it/allows it to happen out of fairness actually. (Yes,sometimes given the hero influx of people in SL2 and how many "villans" there are and how massively restricted those are, it's not unthinkable that the heroes say "Oh shit, 8 vs 2... Wanna get atleast one full team?".)
So yeah alt partying to get game benefits? nah!
But to increase the enjoyment for people in events, given everyone is aware and agrees on it? Why not?
There is alot of work put behind it for the people leading the events anyway. Being able to fine tune each character in the event gives you only the possibility to actually make it fair and balanced much more easier, instead of asking friends to play the one offs with builds actually used for something else. (Most of the time much stronger than a "goon" should be)

I am personally also one of those people that really hates bothering GMs aswell. I respect that they do it in their free time and I feel bad that they would maybe even waste their time for it cause Events...Let's be honest, hosting them is rarely a thing that pleases everyone and it can be really unthankful and easily get out of hand at times not even un purpose, simply cause you overlooked a thing or RP post. I would feel terrible when I even bothered someone who was wasting is freetime for that. (Yes, I have low faith in the community to not be salty fucks.)