Funny how things stick in your memory...MANY years ago, 1965, I bought a Lowery organ and started playing with a band. I didn't know enough to realize I should have bought a B3. They needed an organ player and the local store only sold Lowerys.
I could play trumpet, bass, guitar and drums, but was just learning organ. Anyway I pretty quickly learned to play right hand in C, F and G, then a little in D, but I really had never tried any other keys. The band did a lot of songs in E, and expected me to solo some, so I would use the little pitch bend tab next to the volume pedal and hold it in while playing in F. It bent the note exactly a half step! The first transpose button!
Now, I can play in any key, but as mentioned, many licks work better in certain keys so I sometimes transpose so that I can sing in comfortable keys while playing in comfortable keys. It's just another tool.
I would break a blood vessel trying to sing Misty in Eb. I do it in C. Sue me.
Remember Alfalfa trying to hit those high notes in the Little Rascals. No, not the YOUNG Rascals.