It'd be like saying I always make my own food from scratch — have you seen the state of the burger van down on the corner? You can't trust food made by others.
All frameworks aren't created equal — as with any tooling, you choose something based on the features of the framework but also the longevity, reputation and ecosystem built around it.
Thinking about this case more, this is exactly what you want from frameworks: compatibility guarantees. Frameworks break compatibility, but deliberately and slowly. Will your in-house framework do that? Will it announce and well document its intent to deprecate functionality in favor of new features? Will it find all the users of it across your enterprise and work with them on migration strategies? Will it build in deprecation notices for literally years? Will it build in tests for the bridging changes? Django does all of this, for you, for free.
And even worse when these frameworks are open source and don't even have any accountable people at all, and god knows how many people working professionally are suddenly held hostage by some dude who just felt like going backpacking in south america for 6 months without giving any notice to anyone.