Just FYI, I have two Fedora systems with Gnome (desktop and laptop),with which I usuallly only do system-upgades upon new Fedora releases, no reinstalls. The desktop has been running since F24, the laptop since F25.
Both systems are running fine and fast, with no apparent issues at all.
Unless there are any issues after an upgrade that you can’t fix, I don’t see why a reinstall is required. I prefer to save all the time it takes to setup a new system (installation and configuration of all additional programs)…
After all, this is just my personal opinion - others may think different.