OK, well first I actually think a 10% gap is probably too large for me, but I don't mind a like, 5-7% gap if we actually get some decent job identity. Right now we don't have job identity, we have every single job building to a burst in buffs every two minutes.
And you still haven't actually articulated an argument for why selfish DPS shouldn't be ahead in each expansion. I mean "we can't have selfish DPS ahead because of people whining on the forums" isn't an argument. You said BLM always ahead is "actively restrictive". It's funny you mention that because even when BLM has historically been overpowered, we've never had a tier where BLM was the dominating caster DPS.
RE: NIN and DRG, I consider them to be on the same level as SAM in that they do not offer any extra utility. SAM has a personal mit, just like NIN has a personal mit. It's arguably DRG who's getting a bit shafted here.
But yeah, if you want PCT ahead in burst and cDPS while BLM beats it in full uptime and rDPS, I guess that's fair. It depends on the amounts, I guess.
One final thing: People keep talking about class identity and numerical balance being in some kind of irresolvable tension. I personally think that while they are in tension people overrate how much this actually matters.
This was Eden's Promise. Now ignore the phys ranged and this chart looks pretty good. See how small the spread is? This isn't some unattainable ideal. We had jobs with clear identities and good balance and it wasn't even that long ago!