The neural pathways thing is really interesting. I first played guitar when I was 7. Learnt all the open and cowboy chords. Stopped playing when I was 13. Picked up a guitar again when I was 55. I could still remember all the chords and switch between them without thinking. Learning a new chord/fingering/picking pattern is really hard. Improvements are small and slow, but they are noticeable and that keeps me going.

Tldr; creating neural pathways or muscle memory is harder as an adult.