Concepts seem great, but do they/will they always depend on using templates? Because I try to use templates as a last ditch escape hatch due to debugging/error messages being gnarly.

I'm slowly working my way through the C++ versions (I prefer to use things that are battletested) and mostly loving it except that compiler error messages are just getting more and more esoteric. Or rather, the error messages that have always been esoteric are getting more common since so much of modern C++ features rely on them.