It’s precisely what everyone said would happen.
I don’t disagree with your general point, but I remember that there were many people (on reddit, but also on lemmy) who said there would be lots of power-hungry redditors just waiting to take over and that the admins would thus have no trouble at all finding replacements.
Instead of manually editing the URL you can use an add-on like this: https://addons.mozilla.org/en-US/firefox/addon/old-reddit-redirect/