Because dev-lang/swig is unslotted, swig-3 (default) cannot be installed at the same time swig-2.  Software packages like PSRCHIVE (https://psrchive.sourceforge.net/) that require swig-2 to build the python bindings can't be built without extra effort. (EDIT:  psarchive has bindings for python3 that work with at least python-3.10)

Recently have been building lots of software used for pulsar astronomy, and I'm finding that it works for the most part out of the box on Funtoo more smoothly than on Ubuntu (that also has the swig problem, btw).  We can recruit users by making development by scientists easier.  They know enough to find problems but not enough to solve them