It's all about personality and attitude, anyone can learn to become a better engineer than they were yesterday. The issue is, do they have the resources to do so, are there incentives? Are you making sure they're fully equipped to give you their best? That includes everything from offering training to even benefits, overworked engineers will make mistakes sooner or later.
It is definitely doable if you have a good mentor / role model you admire. I change a lot in my early to mid 20s because one of my uncles took the time to have one on one convos with me to give me feedback on my behavior and why I should do x, y or z instead. It was like I was a completely different person a year later.
Senior Software Engineers should not promote bad habits to juniors.
Absolutely can be developed, takes buy in from both sides.
Unfortunately in tech either seniors aren't available as they should be everywhere, and juniors can.. sometimes.. prefer.. shiny object syndrome and re-learn everything from scratch, until they realize they aren't the first and that's a great thing that will help them go much further, quicker.
