Kicking a player for "low dps" in an area where there are no "DPS checks" (or rather dps checks are in fact being met) ...
(which a lack of regular content having dps checks, and endgame having tight dps checks, is the leading cause of why people cant clear endgame content. I.E. a serious design flaw...)
... is 100% unjustifiable.
Now, if you were arguing with the party members (which you say you were not) then even more so unjustifiable.
When I first returned from a break a month or more after Heavensward was released, I also was kicked twice, except I was given no reason. In fact, I have cleared many endgame fights prior to echo being introduced, and most shortly after they were released (within 1-2 weeks) as multiple different jobs. So to say its because of "low dps" is nonsense.
If you cant be bothered to give a dungeon an extra 10-20 more minutes because someone is new and trying to gear up their job, you shouldnt be bothered to queue up through duty finder. Make a pre-made if you're that absolutely "in a rush."
Also, you dont need to "look up guides" when the guides mentioned are all derived from simply reading the skills descriptions and deciding which actions go where in a string of combos. This is extremely simple to determine. Time is the only thing that makes you more efficient at deciding which actions to place where under certain circumstances, as any "guide" is only going to show one string, that does not fit for all scenarios, thus are a waste of time.
Lastly, if youre that impatient, you shouldnt be a mentor. If you cant take the time to wait, and teach, new players are going to flat out quit, and this type of attitude drives off veteran players (including myself) to also quit, because I will absolutely not be bothered to deal with that kind of attitude.
People who support vote kicking, and justify bad mouthing people who are still learning, or simply doing things in different ways, even if they are more successful, but dont equate to the highest damage, clearly have forgotten you once were undergeared, and learning your job.
You accomplish nothing by bad mouthing players or vote kicking them, except halting their advancement in gear acquisition, learning their job, and often times, encouraging them to flat out quit.