Current problems with machinist and being constructive.

[ForteNightshade]

So why do people bring BLM instead of SMN/RDM who have raid buffs?

Because neither have enough raid buffs for it to make a significant enough difference. At least in ideal circumstances. Reiterating what I said before, Red Mage is actually lagging so far behind that it can't keep up with Black Mage. This is the first raid tier we've had in years where there's more Black Mage clears of P8S than Red Mage. Meanwhile, Summoner plays well into raid buffs enough to remain sort of relevant.

Why do people bring SAM instead of othe melee who have raid buffs?

Samurai is the poster boy for playing into raid buffs to huge benefit. It's synergy with Dancer rivals the Dragoon/Bard love affair of old. The key difference though is despite being extremely effective at utilizing raid buffs, it doesn't overshadow the other melee. In fact, none of the melee contribute much in the way of rDPS relative to their aDPS: i.e., they're all largely selfish. Case in point, let's look at Ninja. In P6S, at the 90%, it's rDPS and aDPS are roughly 100 apart. That's within crit variance range. Now look at Bard and Dancer. Both have well over 1,000 separating each category. Which means a sizeable portion of their entire damage profile is baked into raid buffs. You can't balance a selfish job around that big a margin.

In order for Machinist to even be close, it's aDPS would need to skyrocket. Which, in turn, makes Dancer and Bard worthless. Why play two jobs whose damage relies entirely on other players when you can play Machinist and easily do consistently better damage? It's the Dancer problem now except reversed.

Put simply, even in a bad party, Ninja can still contribute meaningful damage. Bard and Dancer can't.