You can't shoot photojournalism with wide-angle lenses.
You can't shoot studio fashion with just one light.
You can't shoot woman looking natural.
You can't shoot ethnic-looking women for fashion.
You can't shoot black and white ads in major magazines.
Flare is bad.
You can't shoot black and white at weddings.
You can't shoot photo-journalistic type shots at weddings.
You can't shoot portraits unless you just show the persons face and shoulders.
You can't crop out a persons head on a photo even though the person isn't the subject.
I ignored all of those "cannots " as well as others.
I hope that those just getting started out do the same.
You may not enjoy financial sucess or fame, but you will experience the joy of creativity.