So here's multiple facts:

-Melee could not do any of their positionnal, they'd do more damage than ranged jobs. Positionnals are around 500 dps.
-Without the buffs in 5.1, ranged damages would be so ridiculously low, that the 1% bonus in all stat for the whole party the ranged spot bring (supposed to be necessary) wouldn't be enough to make it better than a SMN/BLM/SAM/MNK comp. AKA if the whole party would loose 1% in all stat just to bring a Summoner instead of a BRD/MCH/DNC, it would be better DPS wise (Not better mechanically wise).
-"Mobility" means more responsibility. Since the ranged is the most mobile, it should be always the player handling the most mechanics when possible.
-A very good ranged will have an active time between 94.5% and 95.5%. A very good melee will have an active time between 94.5% and 95.5%. Maybe more, it depends on the fight length, but basically means that you're loosing less than 50 rDPS due to the "mobility".
-A SAM/MNK/BLM/SMN at a 50th percentile (Meaning they're really really average and don't master their jobs at all), would do more rDPS than a 95th percentile DNC/BRD (95th is basically where the player make less than 5 mistakes in their rotation).


If as a Melee, at lv80 and with a similar ilvl to the ranged, you deal less damage than a ranged, the problem is you and you alone.
It's claimed everywhere on this forum that ranged damages are too low, you have to ask yourself "What if I'm wrong and there is room for improvement in my way to play?". There's countless guides and data to help you there.

It's litterally a "Git gud" situation.
I'm far from being a MCH model, but when I reached a 95th percentile, I never managed to deal more rDPS than a Melee/Caster than isn't a RDM or died during the fight.

Damage and all is good but remind yourself that respecting mechanics and surviving is far more important, rDPS is but a single step towards being a good player. Plus, making it a priority will never put you behind a ranged unless that player is extremely good and you are doing below average.