When one side gets the kind of changes they want it's pretty understandable for them to want to keep the other side out of the discussion so that they can keep the changes that they enjoy instead of getting things reverted back, not that I condone it, but it is what it is.
The Sylphies enjoy their easy to play healing and emphasis on doing healing instead of damage, while the veterans find this easy accessibility boring and seek further challenge beyond keeping hp bars up, and both sides have valid opinions, which is why it's important to continue to have these discussions instead of shutting one side out permanently.
That being said, the problem lies with SE and their sweeping changes to healers across the board, what was once a healthy selection of healers with varying degrees of rotational and healing kit difficulty has basically been scaled back so that you'll have an easy time healing regardless of skill level and job choice.
Shadowbringers has been amazing story-wise but in terms of job design it's the most boring and uninspired expansion, and it ultimately comes down to lack of player choice and lack of skill expression. It's not just an issue with healers, remember when ranged dps had actual support skills, or when tanks could play more risky and stay in dps stance the entire fight? Heck I remember having to level white mage to get stoneskin and thaumaturge for swiftcast even though I was only interested in Scholar.
All the jobs are very samey, and the same design flaw extends to healers, they're all easy to optimize, too accessible to the point where it leaves out any element of danger or difficulty when it comes to boss encounters or raids. It's really created an element of monotony when it comes to battle content because so little can go wrong except for people dying, which again isn't too much of an issue since it's not like healers have any mp management issues. Heck tanks don't even need to think twice about their aggro anymore, they just blue dps with either the boss autoing them or not autoing them.
Hopefully come Endwalker they address the issue of making encounters too easy, and add more elements of uncertainty across all jobs and roles like resource strains or harder emnity management, something more to think about beyond the typical tank and spank while spamming your damage buttons. I kind of doubt it and expect healers to be the same difficulty or maybe even easier, but I can hope.