Firstly, playing with others is great fun, and a great way to learn and improve. Not to mention a good motivator. Like you, most of my improvement has been in that context.

When I was just starting out we had "bands" of beginners (guitar, piano, bass etc) and there was a sense of progress learning just one chord or riff etc.

So -how- you learn matters. Equally "starting young" is a common wisdom, but most of the people I play with now "started old". They started because -they- wanted to play, not because someone else wanted to play.

I think method also matters. In school we "learnt" recorder, but it started with "reading music". That's like explaining virtual methods in object orientated design to someone who can't write a for loop.

For both activities we learn better when it's fun.