There are (still!) a lot of copies floating around -- both online and offline -- and it runs on the most pervasive commodity platform that ever existed: 16 bit real mode x86.
Those binaries will boot on anything from an ancient IBM PC with an 8088 CPU all the way through to fairly recent x86 systems (if they still have legacy BIOS boot support).
You have a different meaning of "guaranteed" and "ubiquitous".
It wouldn't be defensible to use those descriptors for Windows XP. In a word, it would be wrong. Calling DOS 3.30 "guaranteed-ubiquitous" is even wronger than that.
Those binaries will boot on anything from an ancient IBM PC with an 8088 CPU all the way through to fairly recent x86 systems (if they still have legacy BIOS boot support).