Yes, having a teacher and method matters. As a cautionary tale, I tried to teach myself touch-typing years ago without either, and it was a disaster. I invented my own 'hover' method using the wrong fingers for the keys, practiced extensively, and as a result ended up having to unlearn bad muscle memory which is much harder than learning the right muscle memory from the beginning. This is apparently also a common problem for people who try to teach themselves the violin.

Unfortunately even finding a teacher doesn't necessarily solve the problem, as a fair amount of teachers end up passing on bad habits they themselves learned and adopted. However, if a teacher can clearly explain the rationale for taking a certain approach if a student asks about it (without getting upset about having their authority/method questioned), that's a good sign.