There's nothing wrong with ffxiv healers, you're the issue.
Let me just start by saying that there's nothing wrong with the healer role and explain why your opinions are going to get ignored again.
In FFXIV the healer role is intended to play differently than say something like WOW. In this game your main priority is to do damage and use your off global cooldowns to heal and sustain the party.
Additionally, the majority of you are players that have mostly touched normal content in the game and 90% of that content is made in a way to support every single player regardless of their knowledge of the game or their skill level, so that type of content will never change.
Even if they did change normal content to make it more difficult I can guarantee you that people will not be able to consistently clear it, leading to some players leaving the game because it's "too difficult" and eventually the thing they made harder will get nerfed and back to it's current state.
Instead of crying about it and trying to boycott I suggest you give a try to some of the harder content in the game such as Criterion dungeons, extreme fights, savage raids and ultimate raids.
Obviously Criterion and Extreme are still easy but they do have a bit more going on, allowing you to use more of your kit.
Moving up to Savage and Ultimates, however is quite a big jump for most people who have not done any difficult content before. Trust me you're gonna struggle and you're most likely going to make your co-healer wanna pluck their hairs out but it's okay.
Now I also know about the thing where certain content was cleared without a healer but here's the thing about that. In order to succeed, you had jobs that have healing abilities take on a fake healer role putting in 4 times more effort into keeping everybody alive that honestly they're better off just going healer in the end of the day.
Additionally, if you looked into it, you'll see that their sacrifice of heals costed them a decent amount of damage just because you can't cast heals and cast damage at the same time. And on the other hand 90% of players will not be able to replicate that, so that alone cannot be a "red flag" towards ffxiv healer job design or whatever this is.
I'm a long-term healer in this game and I've done all sorts of content including the hardest ultimates as healer and from my experience dealing with different healers and seeing how many people actually struggle to play it consistently and forgetting to use cooldowns enough to make me have to cover their healing, I'd say the healer jobs are just fine and if there's anything they need it's just a bit more of an engaging damage rotation but looking at DT I can see us slowly getting there.