Steve Cole posted this on the Federation Commander Forum on January 30 and I thought it was a great summary of why the SFU is Star Trek to me.
Trekdom is very broad, and ADB-SFU is really not any more different from “canon trek” than the various elements of “canon trek” are from each other.
“Canon Trek” is an ever-changing and seriously inconsistent body of work. Every scriptwriter does his thing without much reference or respect to the work of previous writers. That’s why we have warp speed dogfights in one series, nobody can fight at warp speed in another series, and nobody can TURN at warp speed in yet another series.
ADB’s SFU was designed by a military engineer and has been remarkably consistent over 30-odd years. There have been at least five official maps of “canon trek” which don’t look anything like each other, but SFU has one map that has been the same since the first game was printed in 1979. SFU has a specific timeline of events, wars, alliances, and technology; Trek makes stuff up as it goes along without regard to what was done before. (We make stuff up every day but we make up stuff that fits into the existing framework.)
In one very real sense, trek is a literary/fantasy story set within the historial world that is SFU.
Trek kicks out a movie every few years and a series for a few years in any decade. SFU kicks out new stuff every month. The total body of SFU (history, technology, geography) is actually bigger than trek. We have published more ships, more planets, and more empires.