1) the user broke their system because they were installing anything they could and are blaming MS for their troubles
2) the user has no idea how to fix anything so they default to a reinstall because they think it's easier than finding the fix. In a pre-Google/StackOverflow world, this may have been true.
3) The user was on a quest for absolute stability, and was superstitious about uninstalling/reinstalling drivers etc.
As for the "only ever just barely worked" statement, I strongly disagree. Yes, a lot of maintenance and good habits were required, but it wasn't outside of the realm of possibility to have a stable Windows ME. I know, because I'm one of about 5 people who ever liked Windows ME. I thought it was a decent OS, as long as you figured out that the Device Manager had 10 copies of every driver, unhid them, and removed them all and rebooted.