The difference is that with Wayland there are no design issues that prevent you from implementing it reliably and securely; if it's broken it's an implementation problem that can be fixed.
Its not that they still had python 2, its that the binary "python" referred to python 2 on ubuntu (it might even still be like this) while other distros had it pointed to python 3.
Given that python versions are incompatible by design you should probably explicitly refer to the version your code supports. At least that is my takeaway from this mess.
