Flask is a minimal web framework that relies on its ecosystem of packages and tutorials to keep it current and relevant. So yes, this is a problem for Flask if key packages that are recommended in just about all tutorials do not keep up to date.
Key packages are developed by the community so lack of understanding or no cooperation with Parallels it's not really a Flask issue.
Unfortunately the only solutions for this are:
* Join Parallels and try to change things.
* Use different package, there's plenty web frameworks.
* Understand better semver, and python should try to promote this, or move away from semver to calendar releases like Ubuntu/Jetbrains