This is only a consideration if you can pay enough to keep the junior for the long term pay off.
Companies that aren't offering Big Tech compensation find it very difficult to compete on this.
The best juniors will get a job paying more than your company can offer in 2 years. The worst juniors will remain the "still haven't progressed beyond what they could do after the first month."
In this situation, unless the company can continue to offer pay increases to match what Big Tech can offer, it is disadvantageous to hire a junior developer.