Adding four random digits to people's names was a brilliant solution to two common problems with usernames (users wanting the same username and usernames of notable personalities getting leaked), and now they're just going to the exact same system everyone else uses with all of its attendant problems? Fuck off
I'm willing to bet that older content gets a lower engagement rating by some internal YouTube metric. I know for a fact that they grade contributor-accounts based on the regular and frequent release of content. So you get more YouTube Points for doing a dozen 1-hour long videos a week that are crap and forgotten as soon as they're published than a single 1-hour long video that's wildly popular and heavily referenced for years on end.