In Criterion the numbers were close for several melee and ranged jobs, so it's possible, but would you say that BLM or PCT should be doing p. range damage if they had to move too much? When was the last time a fight forced a caster to use Scathe or Enchanted Reprise for movement after optimizing resources and strats?
The thing is that the DPS difference is not necessarily due to uptime but because the devs refuse to balance MCH or the other "lower end" jobs. If a fight forced melees to use 20 ranged attacks, it would feel awful game play wise. Even when allocating resources to keep uptime, like RPR does by moving their strongest hit to get uptime in this tier, melees would just sit there firing weak ranged attacks, while casters have the option to keep their rotation easily by, at worst, losing some potential damage or resources within burst, just like RPR does with Perfectio.
I invite you to play a melee job and try to get full uptime in M2S or M4S. The Stage comboes, Beat 3 defamations, Alarm Pheromones 2, Witch Hunts or Electrope Edge 2 require precise timing to pull it off.
The gap between top and bottom should be lowered, I think we can all agree on that.
However, complaining now considering that melee have to work for their uptime makes no sense, as this was one of the biggest gripes of the player base in EW due to melee uptime being fully free. If the gap is still wide enough, then melee uptime is not the reason.
It makes even less sense when we realize that the jobs that will end up on top when there's melee downtime are BLM and PCT, those balanced within the "top group", not the rest of the ranged jobs. Precisely because casters can still continue their rotation unimpeded as long as they optimize their movement, slide casts or resources.
I think it's good that players can keep uptime by clever use of resources and skillful timing. Should there be more challenges to melee uptime in future content? Yes, but at the same time, not every job is equal. VPR has zero issues with it, and the jobs that struggle the most don't deal the highest damage even if they manage to get 100% uptime.
TL; DR. The gap should be at 5% at most. A difference of 10% or more between PCT and the bottom jobs is too much.