Yeah, but the original Wang CAT4 version of troff was available without the extra license - its in the BSD tree.  Now that was tied to the original UNIX license of course but it was available.   Many (??most??) sites use the vcat program that Tom Ferrin wrote that used the Hershey Fonts to plot the output on a Versatec or later Varian plotter.   The original Imagen which was forked from a Stanford project used that scheme until Adobe released Transcript.

Brian's Device Independent Troff (ditroff) took another license either source or binary redistribution.  DEC for instance, offered it as a layered product to Ultrix, and I think Sun did the same thing.   At Masscomp I convinced management that tracking the sites that had it and which did not was too much of a PITA and if we just paid AT&T $15 and Adobe $1 a system, Engineering could just assume it was there.

Of course, Tim and Dale both saw ditroff at Masscomp and took that (and Steve Talbot's modified mS macros and Janet Egan's set of book making tools) with them to ORA when they wrote the original NutShell book suite.  I'm not sure Tim ever saw the original troff because as soon as I got there, I bought the ditroff and transcript licenses and rid us of the CAT4 stuff.

Clem