I've read the website and all the comments and I'm still totally lost. Guess that means I'm not the target audience? To me a "music drop" is when someone releases a highly anticipated new song.
example (tongue in cheek) https://youtu.be/CJzfTZlEl40?t=38 drop is at 0:41-0:43
("break" and "breakbeat" are also overloaded terms, particularly in electronic music)
E.g. https://www.youtube.com/watch?v=db5f-A-vSyw (drop at 0:45 seconds in the video, thought the countdown to New years that takes up most of the stage should make that obvious anyway)....
Thought it's certainly not a new thing - plenty of classical music has similar moments, e.g. the 3rd movement to Beethoven's 5th symphony: https://youtu.be/xAQFJ1YpFaI?t=279 ("drop" at 5:05 when the horns blast their way in...)