See the top post. The purpose is to try to fix the type system as best as possible by introducing two named conversions, which I called pack and unpack, that convert back and forth between functions taking multiple arguments and the corresponding functions taking a single tuple. As best is possible given other factors such as inout and labels.
The consequences of faults which will not be fixed, and improvements which can't be made as a result, will eventually occur and those responsible for refusing to fix them will suffer the consequences, along with all the users. Languages stall, user leave, sales drop, and people quit or lose their jobs and others get hired.
I doubt the conversions I propose are enough but its a start. It is bad form to refuse something without understanding the options. It may be possible to return to tuples internally without much impact on users. I don't know, although I observe that the function type in the compiler takes a tuple pointer anyhow, though because its C++ I can't tell if that's a single tuple of a null terminated C array of tuples.
How can you be sure Swift won't return to using tuples? Staff change.