Model execution vs code generation

I’m looking for a backoffice example to use with my small bpms (name it a project to learn elixir and phoenix). I found It looks nice, but again it uses code generation. It looks to me, as a newcomer, as if model execution is less known in the phoenix community, or it was abandoned with ? reasons. Maybe the choice for code generation was a (quick) rails inheritance? Anyway, I’m more interested in “model execution”. "A key differentiator is that the […] platform executes the models in the runtime. This contrasts to the approach of generating code (e.g. Java or .NET) from the application model in order to run the app. The challenge with code generation is that it’s inflexible and results in maintainability challenges […]. Here is an interesting link from a very succesfull and relatively young company exploiting and here explaining some principles (contrasting codegeneration and model execution) that I like: .
Here some slides (in English) of someone that was an inspirator of the people at mendix:
What do you think?