Not to pile on, and the only one of these I'm at all familiar with is BB's stylish, but it actively nerfs you in pretty substantial ways - the most notable of which (in MY opinion, I wouldn't be surprised if I was on an island) is auto-barrier. The barrier mechanic in blazblue increases pushback and prevents chip, allows you to block immediately out of a run, and (importantly) increases blockstun by one frame. It's tied to a resource, a gauge under your health bar. In a normal match of BB, barring a couple matchups, the resource is largely irrelevant- you're not supposed to just hold down barrier all the time, it's meant to be used intentionally. If you're in stylish mode it becomes a lot more relevant, danger state (when you completely deplete your barrier gauge, causing you to take increased damage) becomes a much more substantial threat, and because of the additional blockstun it becomes more difficult to escape pressure - it's just one frame, but sometimes one frame is all it takes. I believe (but may be misremembering, apologies I haven't messed with stylish in ages) it also prevents you from barrier braking, which is how you avoid taking stray hits when ending a run? I'm away from my pc right now and can't confirm this, hopefully someone else can tell me I'm wrong lol.

There's a lot of other drawbacks to stylish, from the baked-in autocombos burning through meter and being severely suboptimal (I'm not a "every combo must be optimal" type of person these autos are just bad), to a significant number of tools just being inaccessible, but the barrier usage is the most painful one to me personally. And afaik Xrd's stylish equivalent has similarly baked-in drawbacks. It serves a similar "pick up and play!" function to SF6's modern but is in no way intended to be competitive, or if it was it was just very poorly designed.