As a self-taught developer one key item I see is not the specific language skills but a mindset. Some people have the temperament to be good developers. They have logical thinking skills, good problem solving skills, and decent communication skills. The advantage of an IT degree is you have honed your skills on IT problems during your education. Other STEM graduates have honed these same skills on different problems. Same skills, just applied differently. But the common mistake is to assume all chemical engineers can become good programmers and vice versa.
Learning the actual language is not the hard part, especially if know a few already. The bootcamps and online courses can teach one a language in a few weeks of diligent work. What takes time is learning the existing code base even for the most experienced programming. Add that some industries there is some industry specific knowledge that must learned along with the code base.
This learning takes time.
Bootcamps are expensive and only give you the bare minimum skills to get a job in IT. But there is a tendency to oversell them to non IT professionals. Bootcamp or online course type training would be very useful for an IT professional needing to learn new skills quickly in addition to the ones they already know.