There's two problems with this: first, the new mods have a good chance of being just as bad as the old mods. Second, the new subs will not be able to use the good subreddit names and will be harder to find. The latter is core problem: discoverability. If it was possible to just found a new sub and have it show up just as clearly when you search for subs related to a particular topic, then if the mods turn out to be terrible there's not many problems in just starting a new sub. But as long as only one subreddit can have a particular name you can't solve that problem