This makes perfect sense and is a net good. There were a ton of awful bloodsucking SaaS startups destroying progress for these niches.
People who understand their niche best have taken it upon themselves to build exactly what they need.
The question about junior devs is a red herring. There are no "junior devs" because the title is obsolete. If you want to get hired as a dev, you need to at least show off some projects that pass scrutiny. This is the way hiring always was anywhere that wasn't a coding sweatshop.