> Calling Thing::default() clearly communicates that your just getting baseline values and not a lot of magical other initialization stuff going on— with a Thing::Thing() in C++, you're really at the mercy of whatever the project conventions are for how "fat" the constructor is going to be.

In C++ the constructor without arguments is called default constructor. Of course the expectations depend on conventions, but usually it's something from uninitialized garbage to an empty state.