I took organ lessons for 6 months forty years ago. I had played trompone in school before that,so I didn't have much background on keyboards. After a month,I told the teacher to skip the scales and teach me to read a fake book. In 6 months I was playing out.

The downside was that without reading left hand,I was not voicing my chords properly,so I taught myself to read bass clef as well. While I use chords while playing,a little knowledge of reading and theory is useful.

As for playing by ear, I became a slave to a fakebook. I didn't dare let go of my crutch until I started playing along with midfiles. I played over the melody for awhile and then muted or deleted the track.
By developing your ear for intervals,and finger memory,you can have the best of both worlds.