And this wouldn't be far from the truth. The job had too much "work" in its role in-game, and it was part of why it had such a high burnout rate. Specially when all some of us wanted was to be the guy with a sword that could use magic.
You're right up to a point. It is impossible to have a balanced melee/nuke/heals hybrid in an MMORPG. There's simply too much to take into account if you are truly trying to make it an even split between the three aspects. And you're right, such a hybrid will never see endgame, and if they do it'll be after getting pigeonholed into a role that chances are the people who rolled said hybrid did not want to do. For FFXI's RDM it was buffbotting; for WoW's paladins it was healing.
That said, it is possible to have a DPS with utility in the form of limited healing and some buffs that are easy to cast and easy to maintain. The combat model would still favor DPS over heals while making heals possible but extremely limited. Going to WoW's paladins, if you specced Retribution you spent your resources smashing faces, but if you felt the need to heal you could...at the cost of most if not your entire mana bar casting two or three heal spells that healed nowhere near what those spells would do coming from a real healer. It was fairly balanced, was still found wanting in competitive-level PvP (contrary to some predictions, hybrids did not rule the PvP universe when they were made combat-viable), nor was it topping DPS meters in raids. It was good enough for justify their DPS spots while still being considered hybrids.
That's the appoach I would like to see the devs take.