I find the sign snobbish...
Prideful, egotistical and downright sinful by nature.
My opinion is this:
Pay attention to what you are playing, don't concern yourself with how another brother needs to make things work for themselves and quite judging.
I play saxophone as a primary. I also play keyboards. There have been time that I have come in at a show's call time and the singer has come down with some funky voice tribulation. Now, I am well versed in theory. I am also no slouch on the keys, but let's say that I have been rehearsing this piece for a week in the key of Eb and now their is NO WAY the soloist will ever hit those notes. I opt to help her out and drop the key.
I could with one hour or less time:
1) Try to play all the key lines that I have worked out in Eb in this new key, hoping I do not sound like I just stepped on a hand grenade.
2) Transpose my keyboards to the new key and play as usual. No one is the wiser and I have provided the SUPPORT the singer needed.
If I play on a piano, then I would have to sit down a rehash the chords on some paper just so I would get the changes right.
The transposition feature on modern keyboards does not have to be a bad thing...
Try not to become elitist...
Peace,
Wolfram
P.S. I do play in all twelve keys....