Indeed. Piccolo blew up the moon before Dragon Ball Z even started. It kept trying to "raise the bar" with every new arc in DBZ, and it got silly rather quickly. I still like DBZ, but this is something it struggled with and where turning super saiyan would be a big deal at the end of the Frieza saga, skip forward a bit and Goten/Trunks are turning super saiyan as children with barely any effort just so they can keep up with the constant escalation.
Ah, my fault, I meant the entire Dragon Ball, not only Dragon Ball Z. In the beginning of Dragon Ball Son Goku is already quite strong but not invincible.
Dragon Ball Z lost me precisely because there wasn't much more to grow - I only watched parts of it because of the new children/younger characters who were again 'weak'. But as you point it out yourself, they mastered what took ages before in no time.
