Just throwing something into the ring here for “critical” comparisons:
Crit swapping, the only really relevant way to abuse crits, is probably the hardest to do with Fl4k (and Zane) as they actively cannot do it, except for the conventional way, by swapping to a high critical bonus weapon while the projectiles of another weapon are still mid-air. This is neither easy to do nor even practicable, except for very few select fights.
Moze on the other hand can just hop on her Iron Bear turret (Dakka Bear) while holding an Unforgiven and gets the critical bonus for all her turret shots, making it incredibly powerful. Amara can snipe enemies off the ground with Phasegrasp and use crit-swapping that way and basically transfer the increased damage with Ties that Bind. Zane has, just like Fl4k, no exploit unique to him for crit swapping, although the clone can double-dip in certain bonuses, but that doesn’t affect the critical damage.
Fl4k really is not offsetting any balance of the game in any way right now. And what has been said in this thread arguing against the idea of “Fl4k ruining critical damage” has been proven. It’s really no matter of opinion, we’re talking here about stuff that has been proven by the game itself, the data, the facts. It sounds harsh, but of all the vault hunters Fl4k has the least to worry about balance by far, because they have the least potential for unforeseeable behavior. Amara has probably the most access to mechanical exploits, just by the design of some of her skills and Moze has been at least partially responsible for grenade nerfs in the past.
As was stated above Fl4k in fact encourages critical hits, especially in Fade Away as weapons don’t actually get any critical bonuses, just the Fade Away bonus, which is just not much to be honest, especially when it comes to Guerrillas in the Mist. Hitting true critical hits during Fade Away let’s your damage skyrocket, as it should, but that’s still nothing other Vault hunters couldn’t keep up with. In terms of DPS Fl4k is not even on top, no matter the setup. Amara can one-shot a handful of enemies at once, Iron Bear nukes whole towns in a few seconds and Zane’s clone let’s Zane players go AFK. Fl4k has to coordinate the pet and even if done so flawlessly is often out-damaged by the others or the effort put into holding up with the others is just extremely high and not even worth it.
The one discipline Fl4k currently excells at is crowd control by drawing the aggro to their pet. That’s a cool playstyle I myself really enjoy, but you don’t need that playstyle if you have the damage to kill quick enough and the survivability to survive long enough. The other 3 vault hunters all have that (pretty much) without the need of a specific gear setup while Fl4k needs specific gear to not be a glass cannon.
Last but not least: Just look up the most popular builds for all Vault hunters and you’ll see that most Fl4ks don’t even really use weapons with high critical hit damage bonuses.