I'm currently working with a team of a few seniors and the rest mid-levels. I've helped get a few juniors hired but they've buckled under the pressure after 6 months.
They studied development at school and did great with their classwork but perhaps they thought they knew a lot and ended up realizing that they barely scratched the surface.
Though not required to learn deeper aspects of development, having a team, partner or mentor goes a heck of a long way. It's like learning the piano. You can hit all the right notes but it doesn't mean you have musicality.
American here. If I was at a mall here in the US and heard this kind of bragging I'd roll my eyes, too.
I was once trying to buy some snacks at a market and a person's card was declined so they started bragging about how much money they had in the bank and that the store was wrong. Everyone just sighed and groaned around her.