Do battery isolators damage your deep cycle coach batterys?

Just a comment - we had an isolator in ours and the battery kept giving me trouble. I bypassed it, and now not one bit of trouble with battery or charging. I'm not a tech/mechanic, so have no clue why, but it worked well after we disabled the isolator on a road trip, so never hooked in back into system. have had no troubles in two+ years since.