More often than not, I start my projects thinking that they would be small and don't need a comprehensive framework like Django. Then I figure I need an authentication mechanism, SQL abstraction, an admin site, a pipeline to handle, verify the requests and so on. Then I switch back to Django mostly because I don't want to rediscover the world again. Surely given enough time I could rediscover, but why would one bother?

As per staying lean as stated in the article. I don't think that's staying lean at all. I must mention that I have no knowledge of the framework or codebase of the company in question, although rewriting a codebase is almost never a good idea. Well, it will require a lot of rewriting which is redundant, you would be ditching a lot of testing and bug fixing you have done ever since, and you will probably create a space a lot of new bugs.

I believe a better approach would be componentize your structure in a way that's still governed by django, every component split into apps. And if there are outlier apps that do not need to be within Django at all could be used by redirecting the requests to those services on the load balancer / reverse proxy level.