I think "you plug a grammar into a generator, and you get back a function that maps character sequences to a syntax tree" can be enough understanding for a lot

I think "you plug a grammar into a generator, and you get back a function that maps character sequences to a syntax tree" can be enough understanding for a lot of use cases. Maybe you're more interested in any of the many other aspects that go into designing and implementing an interpreted language -- type checking, garbage collection, an efficient bytecode format and interpreter for example. But maybe you aren't, in which case I agree that case a hand-written parser might be right up your alley! There's no one size fits all.