Marksman is a pretty weak example, the damage it provides is mediocre at best. Because it was used on one boss with a very specific build in one part of the game does not make it useful
It provides the most orbs, and for just hitting something. You can get upwards 6-9 orbs for hitting crits AND killing targets. 6 just by hitting 3 crits.
It’s still much better then all the supers they mentioned
saying Marksman Goldie is too powerful is disingenuous and a stretch to say the least. The damage it provides is pitiful: 180k w/o Radiant, 226k w/, ~380k w/ Star-Eater, and with Nighthawk (double normal damage, btw), its damage should be around 450k. With those numbers, you may as well not use it, especially provided it has only proven effective to have multiple Hunters run in on about 2-3 raid bosses, ever. Also, the super requires you hit crits, which may not always be easy, granted Div exists. Speaking of, with it and Star-Eaters, you should hit ~500k (which I admit, is quite strong) in its current state, but that will drop to around 440k with the nerf.
Honestly if the damage phase is shorter than 30s, it will not be worth using, or chaining, unless your team really needs Orbs. BlightStaff or Sentinel are easier sources of rapid orb gen, and they don't have to be used for bosses only.
Also, I now realise this entire argument is stupid, because it implies that Marksman is used anywhere outside of specifically Kings Fall in the case of this argument, and in reference to one video of a GG only Oryx kill. People have killed Orxy with Lament and Arcius, but that doesn't make them meta outliers