A couple of recent bookings I have made on 56x26 rinks, which would give a theoretical maximum of 728, suggested to me they had maximums of 500 and 300, which sounds more realistic - still a lot of people, but reasonable given that not all of them will be on the rink at the same time and there is a sizeable surrounding area. I think I have once or twice been on a rink where they had those kind of numbers - around Christmas, public session. Not very interesting for those of us who like to get a bit of speed up, but people seemed to be enjoying themselves.
If you think about it, theatres and cinemas would be densely packed too. A rink has the added handicap of people with skates on their feet, but a theatre or cinema has a bunch of seats and narrow aisles to obstruct an escape.