Dunno what made me think of this just now. When I worked for IT in a school district way back in the 90s, a librarian told me she kept a supply of mouse balls in her desk because kids would steal them out of the school computers. What I remember about those balls was they picked up dust and crud off surfaces. Pretty soon optical mice came along and they were history.
Just my own perspective lol. I was an old-school programmer before the web era, when computers were in a computer room and we used “terminals” that were just monitors with keyboards. I only had a PC and ball mouse for like 5 years before I got an optical mouse.