I think a lot of the Kaizo-styled levels were accidents rather than a deliberate design choice. The problem is that it's notoriously hard to judge the difficulty of a game you make yourself. Most people will vastly underestimate the difficulty they create because they think that their own experience playtesting their level is the same experience that a random stranger will have, when in reality the creator will find it much, much easier. Because people wanted to make challenging levels but lacked the experience to evaluate difficulty, they designed their levels so that they would be challenging for themselves, resulting in levels that were nigh-on impossible for other people.
Combine this with some fundamental misunderstandings about game difficulty, and you have a recipe for disaster. For example, I get the distinct impression that a lot of creators think that a lot of people completing a level means that the level is easy, when it might actually just mean that players find the level to be fun. So they'll turn up the difficulty to make things more challenging, removing the fun from the level in the process.
I wish more creators took inspiration from how Nintendo designs levels, but no. Instead we get a bunch of gotchas combined with almost nothing but giant-sized enemies with wings because why the fuck not.
With Super Mario Maker 1, I (almost) always tried to design my levels so that they'd fit right into the game that they were themed after, mostly Super Mario World. I almost never saw other creators doing the same, which kind of removed my motivation to play other people's creations. It's lucky that I enjoy creating levels so much.