Most barriers to entry are not designed to protect anyone, they're designed to preserve power. To protect people from bad products, you need regulation, accreditation, etc.
This is the first step. Then one needs to find a company with a good engineering culture, apply the theory they learned and gather experience. Ideally one should find a qualified engineer as mentor.
Self-study and being aware of developments in the profession are the last piece of the puzzle.
Yes, some people won't be able to do some of these things and as a result they won't be good software engineers. They could still be successful programers, the two aren't necessarily related.