Interesting, after reading your comment I've decided bad UI is subjective. I'm gen z, and never found Snapchat's UI to be confusing, and none of my gen z friends have ever complained about it, either.
> They flock to difficult to use interfaces that become an insider feature for young folks to keep their parents out.
This part might be true on a subconscious level (or it might be part of Snapchat's design philosophy), but do you think younger generations really choose apps for this reason on purpose?
Every interface convention was novel at some point. Breaking them doesn't necessarily make a UI bad, just as following them doesn't make it good. It depends on your skill as well as your audience, their expectations, and how experienced they are with the current interface patterns.
But certainly the vast majority of products should not create new or novel interface patterns just as they shouldn't "roll their own" cryptography -- it is almost always unnecessary and unless it is your primary focus it is very likely that what you come up with will be significantly worse than the status quo.
> They flock to difficult to use interfaces that become an insider feature for young folks to keep their parents out.
This part might be true on a subconscious level (or it might be part of Snapchat's design philosophy), but do you think younger generations really choose apps for this reason on purpose?