LOL if you truly believe this and LOL at your delusion of 99% of applicants having some type of research. In 2017, under 60% of
matriculating students had a research experience (
Matriculating Student Questionnaire (MSQ) - Data and Analysis - AAMC). I'm guessing an even smaller proportion of applicants had a research experience. Additionally, only 8-12% of matriculants have a graduate degree, and that's without distinguishing PhD from post-bac certificate (MSAR).
Sure you could get all the things I mentioned above without doing a thesis, but isn't it nice to have some kind of narrative with a long-term project you can speak about in essays and interviews? Additionally, the thesis program probably provides structure so that you don't have to spend time slogging for a lab that will put up an undergrad and beg for time with a mentor. Again, people haven't done it and so they will say you don't need to do it, but from someone with an undergrad thesis, I will say for sure that it enhanced my application.