You can clear abyss 12 with dps barbara. 36 staring it is another topic.
I personally do not care about tier lists and ultra bis setups. I already have teams that have been 36 staring the abyss since the first year the game came out and continue to do so and I also roll on units that are considered sub par if I like them (eg; Cyno).
Dehya however is borderline insulting. It is not a matter of whether she is meta or not. Most of the myriad of issues she has dont even have to do with how bad her numbers are and people would be willing to overlook that. Her problems end up affecting her gameplay as well and it just goes to show how little care they put into this unit, knowing it was going to go into base banner.
For example, how on earth do her autos in her ulti not proc XQ and yelan ulti? Why does the E reapplication inherit the timer of the previous placed E? Why does ultying remove her E from the ground? Why does placing her E knockback enemies so far that you cannot follow up with autos? Why does her auto string make it so that you cannot land the final punch she does because of the knockback?
This is not a matter of meta but a matter of principle. You can go ahead and get her and her signature weapon if you like her but I find it unacceptable that this is a unit that you potentially get charged money for.