I don't think you're understanding their use case, they aren't building some Flask service, they're an ML drug discovery company supporting research scientists and as such they're more or less building a framework. There's a lot of code reuse and most large orgs building similar frameworks have adopted similar code quality standards - think PyTorch, Fairseq, Pytorch Lightning, Huggingface - which is why tools like MyPy / PyLint / Black exist. For people who have used those libraries there is a night-and-day difference between the anything-goes ones and the ones that do linting and unit testing.