I googled it. I did not know vi before that, and now I use vim as my main editor for code.

So you did not just "learn vi by just using vi". You have also used a browser, google, and tutorials found by google. There is nothing wrong with that. In fact congratulation on learning vi! But sadly your example does not illustrate that one can "learn vi by just using vi".

The intro screen tells you exactly how to open help and exit. Man gives you even clearer instructions.

If you just launch vim it tells you the basics of how to use it, and how to get more help. So it's definitely possible to learn it without external resources.

Emacs is the same.