I wonder in which language you think 1m locs would be manageable for an actual monolith (and not just a monorepo).
And method_missing is a such fundamental part of the language, that it obvious you skipped basic docs on the language. Besides that, there're not many "magic references". Unlike in python, btw, where "there should be 1 obvious solution to any problem" mantra doesn't hold for a veeery long time.