The big subs that they would 100% do it on that are a few million plus, you would never really notice. /r/pics, /r/gaming, etc who even pays attention to who the mods are. The mods aren't the community.
If Reddit replaces volunteer mods with paid mods we would get a more consistent moderation and almost certainly a more professional experience. People getting banned for disagreeing with a mod would stop for example. You wouldn't have to guess what the mods mean by their rules. For example, on /r/startups replying to people giving them an answer and saying if you have any more questions I'm free is called an unauthorised ask me anything. Which is crazy. There are many subs where it's anyone's guess what the rules are. And it can literally depend on the mood of the moderator. There are some subreddits that automatically ban people who have posted in certain subreddits.
Moderation is an important job. It's needed. But I can't think of any other social site that has such a bad rep for moderation.