I hate that kind of not-invented-here syndrome. The project I am helping develop is partly open source and has its own server-side framework, its own ORM and its own typescript based framework. Community-wise we are dead in the water, because nobody wants to adopt to the own frameworks.

Incidentially, I used OpenERP5, which is an early predecessor of Odoo. I hated the interface with every fiber of my being. Due to some custom development, we were not able to upgrade to more modern versions.