I don't quite understand this point. Why does the exact starting point of tinkering (existing .vimrc vs a completely blank one) matter, unless you somehow think the empty .vimrc defaults are the most sensible?
Like, there could be a bunch of features that are barely used and not discovered, but seems like the easiest way to discover new features is to scan through a good .vimrc, rather than sleuthing through online resources.
Starting with a blank slate lets you refer to just the program's documentation to configure it, while if you start with a config bundle you'll have to refer to both the program's documentation and the bundle's documentation, and you'll have to be decently familiar with both how the program works and what the bundle does in order to make creative customizations.
Using a configuration bundle makes the learning curve less steep but more tall, essentially.
Like, there could be a bunch of features that are barely used and not discovered, but seems like the easiest way to discover new features is to scan through a good .vimrc, rather than sleuthing through online resources.