Having been playing a long time myself, I've never felt, personally, like I wanted to do content without a healer. Is it possible? Yes. Its also possible to do a lot of content without a tank. And its also possible to do a lot of content without a DPS, too. I remember doing stuff with nothing but tanks, or all white mages, ect, all the time.
I mained Monk through ARR to Stormblood and switched to Gunbreaker in Shadowbringers. Healing has always been my second role. The only complaint I've ever had is it would be nice to have more to DPS than 1 DD, 1 AOE, 1 DOT. But I don't see how a whole array of DPS abilities would work with limited hotbar/controller space without fundamentally removing the vast majority of healing options.