This will mean a virtual memory allocation of 800 GB. Such large allocations can fail, even if virtual, depending on over commit settings.
Given how Go has no issue being prescriptive as hell on other things, I don't see why they couldn't just go "set vm. overcommit_memory to 1 and fuck off", that's exactly what e.g. Redis tells you.
And again it would hardly be the first time Go makes OS-specific decisions.