Good question - it’s mainly because button mashing is kinda funny, easy, and surprisingly effective. Definitely not the only way, I’ve found there’s many flavors of time stretching each with their strengths and weaknesses.
To build a time stretch patch that uses retriggers I usually start with two trigs on a single track just like my older video, then add some “event” triggers with parameter locks that I give the fill trig condition to, then once I’m happy with the single track I copy that page of trigs over to other tracks and add some microtiming offsets or change the retrig rates slightly to smooth things up. Hope that helps and thanks for the feedback