Barrage is not the best single-target choice for DPS regardless of who you are, you're wrong.
Steady Focus is a terrible choice across the board, generating less extra focus than you save with Thrill, you're wrong again.
PS doesn't fall short on single-target with 4pc for any reason.
Drop the pseudo-science, 100-120k single-target bursts are not high, at all. It's actually on the lower side, considering people (myself included) were doing higher bursts with around that iLvl back in BRF, where Aimed Shot wasn't instant. Unlike you, I can prove what I am saying rather than pull BS out of my ass. 702 iLvl, BRF in April, 150k burst:
https://www.warcraftlogs.com/reports...done&source=21
That was a remarkably unexceptional pull, too.
Plenty of people use PS, you need only look at logs for the only single-target boss where you'd use it (Fel Lord Zakuun), since he is the only single-target fight in the instance. So hard.
Also, Haste exists, Powershot takes like 2 seconds to cast the majority of the time.
In 2 seconds, you can generate 14 focus with Steady Shot and that's it (plus passive regen, but you do that with Powershot as well). That's not enough for an Aimed Shot, it's not even half the focus needed for a ToTH Aimed Shot.
You have no logs attached to your character, you've barely done anything but LFR, and you're pulling pseudo-science out of your ass. You have nothing to base your arguments on other than what you're saying, you can't even claim to have performed well with your anecdotes.
Also, enchant your neck.