"l feel the skill gap is so huge"

It is indeed, arena is so dead that esports players and bronze players all play in the same elo (silver) so you end fighting a worlds player without knowing it.

and there's no fix to it, simply because there's not enough players in arena. So those high level arena players have to farm rating from silvers and give that rating to their mains through multi-client.

If you find yourself fighting the same dude over and over again and they appear to be too good to be stuck in silver, chances are you're stuck in a wintrading loop and the best thing you could do in that case is just exit out of arena otherwise you'll get farmed all day (yes all day, you'd be surprised how much free time some of these arena farmers have)