A mentor would definitely be helpful but they are significantly less necessary. e.g. I've been programming full time for 5 years and have had no mentorship - I learnt everything online. I've also worked solo from home the entire time so haven't had any help from other programmers which would have been available had a been in a standard work environment. I probably could have progressed quicker with a mentor and it would have been helpful but it's not as necessary as the way it would have been pre-internet.
