You can delete the old Steam folder after making sure your new games run fine and saves are backed up. It won’t affect your data. If you want Steam to detect old installs instead, add the E: folder as a Steam library in Settings - Storage.

Have you even remapped the steam library in storage settings menu.and why will you reinstall or moved already installed content, that might already have worked on previous pc.

Newer games might need SSD or is even bigger then past gen games so size on them require even more space or faster spin disk then past spin disk, again, only you know what you have bought, you dont mention size and media type SSD or HDD, speed and type matter more today then in the past, even size 10tb spin disk is seen as cheap today, so why move old content.

I'm sorry if this look like complicated then it's not.


We could also said old game that work fine on old spin disk, keep them there.
you only move games that load alot to SSD for speed even when they say work fine on HDD.

example fallut4 is one of them, and you can find many other games like that.
or total war that load map and battle map, even older total war games.