Sure you can try to become an all out tank in 10 seconds, but that is one of dissipation's uses. Simply put if we talk about saying how dissipation doesn't have a day to day on casual content, in theorycraft or meta talk that is true. The numbers don't support it since we waste alot of resources for an ability to simply say correct the mistakes of others when we can wipe and just redo it for instance.
But when you do it in practice, this is honestly a skill that has more uses than we can describe. It isn't just the situation that makes the ability worthwhile but how we use it in any situation that makes it amazing. A more perceptive healer is needed to make it work that is all i can say from my experience using it, even in normal everyday content.
I want to help you understand, and well this is probably the best way i can put it, if you look at the big picture why it can't be compared to something like divine seal/syntary in normal content usage is that unlike WHM/ASTs we carry alot of survival utility that is amazing when they crit or when used in one hit situations. Dissipation helps us unlock all this utility at one go(aetherflow assuming you had none) with enhance healing power and gives us the option to mitigate just this one attack or recover from it. But we can't jump right away to say it is an oh shit button, instead it is like a mitigation utility refresh, something which we never really seem "need" since most of the time we assume we have it all under control.
You need to be really good at using your utility to find some use in this and well prepared ahead of the fight. If you still feel unconvinced, then all i can say is wish you the best of luck hoping that this one skill alone gets buffed.
