I think you just hit the nail on the head why I spend so much time storing and organising in onenote, I always thought it was because onenote search is good, it's not, it's because the system search is so poor.
voidtools' Everything (https://www.voidtools.com/) is one of the first things I install on a new Windows system. Instantaneous filename search.
Windows’ built-in file search becomes embarrassing once you’ve used Everything. Though Windows search does save me from having to trawl through settings/control panel.