A company I worked at decided to rewrite a Fortran system - I suspect that if they wanted to avoid a rewrite they could have started breaking bits off into C and mixing the languages at the linking step... but I understand their desire for a clean break - a rewrite was going to take years but a migration would have taken even longer and been even harder due to the lack of Fortran developers.
I agree with you. And that is where I was at that time. I did not have enough experience as a Software Engineer, nor with CakePHP — hence decided to rewrite. Mistakes were made.
I've been there at least once before and boy was that painful - I already have problems to deal with without someone from another team white-anting us with his ideas (that he doesn't need to maintain).
Rewrites usually start with a gap in what is available and what is needed: missing functionality, existing frameworks getting obsolete, difficultly maintaining code because of the existing implementation complexity, costs, scalability issues, compliance challenges, etc. Most of these things serve the business more than the engineers.