Thing is, it's objectively not just "high level players". Check this link,which shows the 25th percentile values of DPS classes in e5s-e8s. BRD and DNC are still squarely at the bottom; the gap is just smaller.

And re: "alot of those peak numbers are without [buffs]" - that is also straight-up false if you're referring to the the default FFLogs view (such as the one linked by the guy you replied to), which shows "rDPS", i.e. your dps plus what your buffs give to others minus what others' buffs give to you. It's your total contribution, in other words.

Of course, these differences are relatively small across the board, and unless you're in the very tiny minority doing world first progression or speedkills, it really doesn't matter, and you should play whatever you want/are good at. But empirically, phys ranged (well, mostly brd/dnc) do generally do lower dps than other classes across all skill levels.