I dont understand the "proper use" for MRVs then. Okay we get nicer types, record types, to do them; but they are otherwise perfectly doable and with little ugl

I dont understand the "proper use" for MRVs then. Okay we get nicer types, record types, to do them; but they are otherwise perfectly doable and with little ugly boilerplate using classes. The "either values", or sum types/ tagged unions I mentioned, are the thing that Java really lacks (and because of that the exception system got heavily abused IMHO).