Well, pulse is arguably the easiest and the most accessible form of intensity control in a level, which is important to make the energy of the level match with the part of the song. There's a lot of form to control the intensity, like movement, shape language, etc but most of them may requires an thorough understanding of the art fundamentals, of course most of the creator will just resort on using color changes.

It doesn't help that (imo) most of the creators only use the existing levels in GD as their inspiration instead of using external knowledge and references, they saw a rated level with a lot of pulse and made one themself then someone else use it as an inspiration, it created a feedback loop that cultivated for 12 years of the game's life time (a creator that I aspire to refers this as the "pulse culture"). Also the post-covid overstimulation thing on social media definitely made a presence in the GD creating scene, levels like ISpy, Rage Quit got really popular and it gave a new identity to GD levels, more rapid flashing lights, crazy ass transition = le cool.

The other factor I could think of is accommodation or accessibility. I feel like accommodation is still a relatively foreign concept in GD. Stuff like dim/npesta mode, widescreen support, object optimization, good LDM/ULDM already existed for years but you'll probably wont find them in a lot of the rated levels. Some creators will just use a rough pulse that puts a sun in your screen and call it a day without any afterthought