I mostly agree with this, but I've been a big fan of having primitive types in config. Most of the time if I have something I want to configure, it's either one of the following (or a map/list-based structure consisting of):

- scalar value

- feature toggle

- URI/enum option/human readable display text

Having float/long/boolean is trivial to validate in the config language itself, and if they're useful and simple enough isn't it nice to be able to validate your config as early as possible?