Yes, Cait has "wave clear". But is no where near Sivir or Lucian.
Yes, she does damage with headshots......... which come every 7th auto attack (every 3rd or 4th when in brush, but as adc you don't often stay there).
The other way for her to use her head shot requires either targets to step on traps (hence her power to siege) or her to net them using her only escape offensively.
And about her escape. It is nowhere near the level of Lucian's, Ezreal's, Tristana's or Graves. Its an escape, yet is mediocre.
Her thing is taking towers. Damage potential?
I mean, sure, adcs build GLASS CANNON. Ofc after a bunch of items they will do damage. Yet there's only 4 adcs that do less dps than cait on single targets (Graves, Jhin, Sivir and Ezreal). Despite that, they are top tier picks.
Jhin offering long range support and engage. Ezreal offering kite for your team. Sivir having engage and disengage as well as team fight damage that outdps cait (in killing 1 target cait in better, but in team fights sivir W will crit). And graves being more of a bruiser than adc, as well as played in jungle.
Cait's deal is traps for siege. If her traps become to weak, she will move to the trash tier. And people will play Trisana/Jinx/Ashe and zone control mages for siege.
That's what they wanted to do in "adc update". Give a different niche to every adc. If they will nerf cait's traps. Her niche will dissapear.
That's why, nerfing other parts of her kit (if she is deemed to strong) is better, than nerfing her traps.
She's played in LCS because they value siege and objective control, at which caitlyn is good. Same reason they spam Azir even after multiple nerfs.
Anivia can also do the same thing, kind of strange she ain't played as often. And I'd argue she's better than Azir, but whatever.
LCS meta is not always our meta. We don't lane swap for example, Tryndamere is still viable, etc.
I value lane dominance and easy mechanics -> hence I'm playing MF as ADC.