You're both trying to make the exception the rule. This is a fallacy.
I wish I could play with those groups shown honestly such dedication is rare. I commend their efforts. How many attempts I wonder.
Do you believe the feats they pulled to be easy? Or without the reasonable effort of precise teamwork?
Most of you are not as good as you think you are to coordinate such a feat let alone attempting it in every encounter, That's why it is nonsense.
Observe the very specific class stacking occurring? You don't just bring any ho-hum DPS job you want on board but the ones with the most utility.
You'll have to excuse my obtuse point of saying remove Tanks as you are so inclined. @ThorneDynasty However, as our friend, Rolder just showed content can be attempted likewise with just tanks so perhaps my example was misguided.
Look I understand the appeal of giving DPS one additional healing cool down for accidents, but the whole philosophy of a Player who chooses to heal is to take the DPS loss so that you can DPS more. I won't even bring up the futility of trying to remove White Mage from a Final Fantasy game of all things. I've seen MMOs go the path where you can build your own character with whatever skills you want... The gameplay of MMOs always gravitates back to the trinity. I've also seen what happens to classes when you give too much overlap. I've actually spoken with professionals in the field who have done class design. I can bring forth any questions you want to people I know for good measure to see what they think. They'd most likely give you similar answers.
You should redirect your efforts twofold. Ask for more dps options for healers as I had previously stated and to have bosses do more outgoing damage with more punishing mechanics.
If not accept the reality that what you are asking for is hegemonized class stacking where only people who play the "right job" get to do content and everything else may as well not exist.