I don't think there is an 'official' stance. I've seen this discussed on mailing lists etc. The consensus seems to be that tagging them separately is better, in principle, because it captures more detail, but it's a lot of work to do it well. This applies to the footway and to the cycleway. And when it's done wrong or incompletely it breaks routing. Pedestrian examples:

https://www.openstreetmap.org/directions?engine=graphhopper_foot&route=55.95252%2C-3.20731%3B55.95313%2C-3.20714#map=19/55.95293/-3.20728

https://www.openstreetmap.org/directions?engine=graphhopper_foot&route=55.95313%2C-3.20944%3B55.95293%2C-3.20960#map=18/55.95255/-3.20862

