I've built a team from trained-up junior devs, and it was great, I would recommend this route for anyone building a team. BUT... you have to have people who can train and teach as well as code. There are personality traits that don't align with this. The typical "aspy Dave" stereotype of a rockstar programmer is not good at this. So you have to align the entire team from day 1 as being a training environment as well…
When I ran my tech recruiting business, I made screening tech resumes a key part of the interview process. I could onky get it to work if I wrote the job ad myself (as a recruiter who talked directly to the hiring manager), told the interviewees specifically what I was looking for, and specifically coached them to find reasons to like people.