My copy is from when I played the organ at church. Your link to where to buy it is helpful.
However, a real musician wouldn’t have problems in playing it, in the same way we play from a “fake book”. True, the problem is that many organists play the notes but have little musical talent, but that is another problem...
I suspect many of us hesitate to volunteer to play the organ because of the lousy music etc.
I prefer having the full score because I am a MUCH better sight-reader than I am an improv player. I think it depends entirely on whether you came up through the jazz/pop side where improv is a way of life, or whether (as I did) you came up through the classical side where improv is something that you get in advanced classes specifically for that purpose. I never got that far. :-D
And this music could not have been lousier - except for one decent tune (albeit with different, tacky words) that somehow sneaked in. I would probably have done better without the score on that one bec. it was different from the accompaniment in the Episcopal hymnal, and my fingers kept going, “Wait. What?”