Thanks for the comments everyone.
Just a clarification: I’m not asking whether we should dissuade users from using Python 3, I’m trying to explain that (on Ubuntu/Debian, probably the two most used OS, also because of the availability of binary pkgs) using anything but the system supplied Python environment is currently not a straightforward process.
This is more about package/module search paths than anything else, but it would appear that new users really struggle to understand what is going on. Somehow Anaconda is one of the ‘alternative’ interpreters that seems to come up the most on ROS Answers questions.
My recommendation is thus to draw their attention (‘warn’ may be too strong a word) to this, so they can avoid spending a day trying to figure out why catkin_make and their simple rospy scripts are failing.