Well, Rudy would have tried to get the Caretaker to send them back, and I'm not sure why the Caretaker didn't.
Looking over the list of episodes before Equinox, two truly questionable omissions are the Vidiians and the Devore. Most of the other events were one-off occurrences, and we can assume Equinox had its share of those simply by taking a slightly different route. You had shipboard events (Tuvix, Real Life), singular mission events (Time and Again, Rise), anomalous events (Cathexis, Non Sequitur) and interspecies events (Basics, Deathwish). But it is very likely Equinox would have encountered the Vidiians (albeit without the Klingon bait aboard) and the Devore (who would have commandeered Equinox due to the presence of any telepaths).
Funny, looking at the Equinox crew manifest - it seems the crew consisted entirely of humans. Anyone ever notice that?