>>105909591 (OP)It doesn't, it's a myth made up by tech illiterate low IQ monkeys. Registry entries left behind by programs take up like 1KB of space and are inactive if there's no program installed in the first place, and nothing prevents you from going into Registry Editor, opening the Find function, and typing in "Firefox" and deleting everything related to that name, or just simply deleting the main entry under Software tab.
Cleaning out the file explorer from left behind loose files is pretty simple too if you are not tech illiterate, mostly it'll just be a few files in User folder like Desktop/Downloads/Documents/Pictures/Music/Videos or in AppData/Local, AppData/LocalLow, AppData/Roaming, or inside Local Disk, Program Files, Program Files (x86)(, and ProgramData. Unless you are low IQ cattle, navigating a simple file explorer and deleting folders named "Mozilla" or "Firefox" shouldn't be too difficult.
Beyond that there's nothing else that could "build up", every single cumulative monthly update runs a dism and sfc scan nowadays making sure that corruptions of files are kept to a minimum, and every yearly major cumulative update makes sure the OS is practically fully re-installed and all files verified.
But none of this matters anyway, even if you leave these registry or file explorer remaining files alone it won't impact your experience at all for the most part.
It's just that cattle like /g/ often uses debloating scripts because they are retarded subhumans that can't figure out using the group policy editor or registry editor, and apply some indians or fat old white dude's scripts which end up breaking all automatization like Disk Cleanup, Disk Optimization, Windows Updates, Security Scans, and they end up with a fucked system that needs to be manually tinkered with while being completely tech illiterate and too retarded for that kind of workload. Tough luck.