tbh this level was only like 10% annoying at best, which is obviously ignoring that you gave a quick exit for people that don't want to deal with its ****
The funny thing about this level is that the way that it's built (having a room for each bad level design or terrible level designing philosophy) isn't supposed to be outright annoying. It shows examples of bad level design. Granted, it won't be too annoying to deal with, since you already knew from the very beginning it's going to suck for purpose and these sections are pretty short. I do have to say that if the real deal often revolves these level design decisions, then this one is most likely going to be a stinker.
The door at the beginning was made for someone who goes through 100 Mario Challenge and don't want to waste lives on that one without needing to skip that level. But at the same time, it could become a bad level design when the maker left a challenging/impossible level, but for some reason didn't bothered to play test it and put doors warping from start to goal.
Pipe #1 in this area is Inescapable Trap. The example I shown may sounds crude by its concept, but the point is: if your level contains an area where the player can't escape just because they picked the wrong path, then it's more frustrating than challenging.
Pipe #2 is Blind Jump. Where exactly should you land, if you can't see the land below you? At this point, it becomes a guessing game rather than pure skills.
Pipe #3 is Excessive use of precision jumps. This one's pretty self-explanatory. If it were to be longer, it would easily become tedious. Who wants to do the same thing over and over and over consecutively?
Pipe #4 is Build-a-block segment. It consists of an empty room... filled with invisible blocks. Similar to Pipe #3, this one can get tedious if it gets too long.
Pipe #5 is Sensory Overload. There's so much stuff going on that it's not even a challenge; it's about getting lucky to get past that segment as fast as you can.
I don't remember what the last pipe and the few doors lead to. But, you get the point.
If you really want me to make the worst level in existence, I can quite easily blend all of these elements in an obstacle course to frustrate the player as much as possible. How fast will you give up on trying would be the real deal here.