For folks running binary only systems from Masscomp/Sun/DEC/HP/IBM and the like, it is possible it was different. The fact is I know Masscomp supplied ditroff on all systems and just ate the $5 license fee. We also license transcript from Adobe and included that. My memory is that was just a one-time charge and no redistribution. I'm not sure what Sun did, but I think they supplied the BSD troff, vcat and the like (Larry may know for sure). I'm pretty sure HP supplied at least the BSD/vcat family; but they have updated to ditroff. I've forgotten what DEC settled on. By the time of Tru64 it was ditroff on the system, but with Ultrix it may have been you got the troff/vcat off the BSD tape had their was a fee for the ditroff/transcript package.
Off the top of my head, SGI also did this. Man pages in the standard IRIX distribution were provided pre-formatted ("catman") and any sort of roff was a separately available, for extra $, product called Documenter's Workbench. I know that this was the case in IRIX 4 and 5 (early-mid '90s), not sure about earlier, and I believe that IRIX 6 finally rolled it into the standard distribution.
The trouble was that if you had a package that provided standard man pages, you had no way to format them unless you were able to get a hold of groff or the like. Not an ideal situation.
-Henry