I think that he meant that Django has a bigger ecosystem with a lot of different apps, so you don't write everything from scratch. There are apps for migrations, building a REST api, having a tagging system, integration with search engines and many others. I won't comment on the state of the Flask ecosystem, because I don't know it, but I imagine it's smaller.

Here's the reality though: so many of those apps in the ecosystem are half-baked, unsupported, and don't actually work. It's a mess trying to match existing code to a set of customer requirements, all the time with the customer saying "Can't you just use django-foo?" ignoring the fact that django-foo was last upgraded 5 years ago and won't work with anything newer than django 1.4, and doesn't do half the things in their requirements anyway. It's pretty rare that any of those applications in the ecosystem actually save me any time.

There are plenty which are production ready and good quality. Some examples that I use are haystack, compressor and rest-framework. If the customer tells you to use a shitty app, explain to them why you can't. They don't know better. You're the expert.