That’s basically what the other person was trying to explain to you
M4 has a few GCD’s that force you off the boss with no possible way to alleviate it; you just have to take the downtime. But other than that basically everyone just does this fight with melee uptime strats (not that you really have to vary almost any strat to actually give melee good uptime the default strat just has melee uptime)
Meanwhile you are reducing caster uptime concerns to “lol just do it”. When you are progging a fight you have a limited number of uptime tools for movement and you have to learn over multiple pulls when to use them, which one to use where and how to minimise DPS loss. You often have to go back change and correct your plan over time to ensure you maximise it and sometimes you still run short on casts
So basically you are comparing the fact that melees have a few instances of enforced downtime but basically get their theoretical maximum by default to casters who theoretically have higher uptime (except in instances where there is simply too much movement to handle which affects PCT and RDM worse) but actually have to learn to map out their entire rotation to facilitate it
In that setting I see caster as the harder role but back when uptime concerns of the melee affects danger for everyone I saw melee as the harder role