Eh? Where's that come from though? I'll cite a few examples from other games I've sunk time into right now:
In Everquest, healer's were generally fine, clerics were the most indispensable healer for raiding whereas Shaman and Druids were stronger for, merit farms and soloing. The only time I actively complained was during one of the planes expansions, the Shaman kit for the new level cap was a literal copy and paste job of the previous to the point where they actually forgot to change some of the tooltips with the new names
In FFXI again, healers were in a similar boat, just this time they didn't have the soloing capabilities that EQ healers had but that was fine. This time round the Job system was actively used as a tool to find the right job for the situational at hand. Even the jobs themselves offered a good amount of flexibility. I mained BRD with a side of WHM, SCH and BLM, if I ever complained in FFXI, it was about RMT or Linkshell politics, that was it. What the game lacked in pace compared to modern MMOs, it easily made up in community, danger and immersion. It was a great time to be a support/healer.
Moving up to WoW, I mained a resto>elemental Shaman and almost exclusively PvPed throughout Vanilla, BC and early WoTLK only stopping with the release of Arena. My own 'complaints' here were rather tounge in cheek snipes at Tigole for the constant Rogue vs Shaman 'adjustments' that seemed to come each patch. In fairness most of them were needed even if a few of them were a bit lame. However in view of this thread, it has to be said that healing Shaman had 2 huge peaks during early WoW and playing during those points was an unforgettable highlight. It's why I have no interest in the PvP in this game, not because it's bad in it's own right, but because it just doesn't live up to what WoW had going back then.
Two more recent examples would be SWTOR and Warhammer Online, both games had excellently thought out healer implementations that did a fantastic job of feeling impactful and powerful in their own right without being quite as devastatingly capable as WoW pvp healers sometimes were. I've sung the praises of healers in both of these games on these very forums on multiple occasions TBH so I can only assume you missed that? Complaints here? IMHO These games both died for the same reason, not enough investment in content development.
And yes, I'll also chime in that FFXIV's early game healing experience is actually pretty great, leveling dungeons are a highlight for sure. Running Bardams for the first time when SB launched was a fantastic experience, so much so that I recorded my leveling grind in it.
So there's 4 rather verbose examples for you right off the bat. Could you expand on where your view came from? It honestly feels like an opinion you've made purely from reading these boards and not much else, certainly not actually speaking to healing stalwarts elsewhere.