I think, as in so many things, moderation is the key. You want to discipline your kid but not be abusive, supportive but not to the point you don't reel them in occasionally, establishing limits and rules but also rewarding them with responsibility, giving them freedom to chart their own way in life but curtailing their dumber impulses and forcing them out of their comfort zone, etc etc etc.
My old man gave me spankings or slaps across the back of the head... but in retrospect it was only ever when I was doing shit that reached max levels of 'being a little shit'. My mom was supportive, but never yelled at an instructor at a parent teacher conference about my shitty grades. I had chores and a curfew, but I was also trusted to take care of my younger sisters on my own once I was a tween, my parents pushed me into sports and clubs when I was younger, but also supported me when I did find stuff I was passionate about.
I think the problem with how Greg raised Steven is that Greg was so convinced his childhood of curfews, meatloaf, and school clubs was paramount to prison that he's basically been opposed to putting any kind of boundaries on Steven or pushing him outside his comfort zone at all. He wants to be Steven's buddy, not his father.
As a result Steven's only experiences with dealing with stuff outside his comfort zone has been life or death struggles, alien invasions, and playing therapist for a bunch of aliens with PTSD, trauma, and relationship hangups while his dad tries to fix every problem with songs and ice cream.