Django provides more functionalities since it is a macro framework.
However, for bio-databases, the main purpose is to present data. Authentication and data uploading are merely seen. Even though some bio web-portal allows to upload users’ data, this usually won’t be added to databases. Usually, web takes users’ data, processes it, and returns results to users.
Django uses models to construct data structures. Models are too complex if no new future data. The initial data usually are predefined before the web is ready. Using fixtures to initialize the database probably will take a while
Restful API is complicated compared to Flask. Middleware configurations and views are annoying.
Overall, the nature of bio-webs is simply to present data. Instead of spending too much time on backend, efforts should be devoted to advancing visualization techniques.