1. Enthusiastic employee (vibe-)codes a replacement for a turnkey SaaS product that the company uses.

2. Company uses it, maybe even starts to rely on it for important business operations, and for a time the employee supports that app.

3. Bugs creep in, feature request pile up.

4. Employee either leaves the company or moves on to another project.

5. Pain

If I understand correctly many organizations will not develop original stuff internally, because nobody internally wants to be the one is shouted at if something goes wrong.

If software already exists that does X, X is a solved problem. You didn't hire a developer to solve already-solved problems.