Just confirming if I understand this correctly: they went through a big chunk of existing code, and then made any internal symbols used in that corpus accessible via //go:linkname?

I don't know why, but I (stupidly) assumed that they wouldn't allow new code to be written that uses those symbols, while allowing old code to work. :)

This explanation makes a lot more sense. So, you can keep using the symbols exposed with this change (until a future release hides/changes them), but cannot use any other internal symbol(s) anymore.