Honestly I think a ton of groups are sleeping on Machinist for that reason. They see that it does marginally less damage than the other R.Phys with full uptime, but ignore the fact that it interacts well with downtime due to having incredibly front-loaded burst damage tied to short cooldowns.

Same shit happened back when TEA released. Machinist was probably the best R.Phys for the fight because it interacted well with Phase 3's frequent downtime, then could store enough Heat and Battery on the lead-in to the final phase to just shred Perfect Alexander (IIRC you could perform on-par with a melee DPS for the final phase when you did it correctly). Was underused because Bard was obscenely strong during the first two phases when it could cleave, despite falling off hard once you actually started progging the 2nd half of the fight.