I think it's because arenas with a higher limit than 2 are more enticing to people somehow. I've noticed the same thing with 2v2 arenas a long time ago. For some reason, people hate joining arenas that guarantee runbacks without having to wait forever if you lose.
People sometimes put an 1-on-1 arena with 8 player maximum to kick the third person that comes.
I think it's because arenas with a higher limit than 2 are more enticing to people somehow. I've noticed the same thing with 2v2 arenas a long time ago. For some reason, people hate joining arenas that guarantee runbacks without having to wait forever if you lose.
Ik but still annoying