There is no point, to me, in insisting that the only right way to work is to put all the creative control into the image capture. Film and digital capture medium differ enormously when it comes to considering when and what kind of creative control you have: this should be taken into account when considering what kinds of filters and such are necessary.
When I was shooting film, I carried B&W filters (deep blue through deep red), color adjustment filters (warming, cooling, Tungsten and Daylight conversion) as well as NDs, polarizer, and occasionally effects (soft focus, light crostar, etc). The creative rendering control with film is mostly up-front, at capture time, so it is important to get it as close to dead-on as possible in the camera in order to deal with the constraints of what can be done in the darkroom.
Now shooting digital capture, I have abandoned all filters except for occasional use of NDs, polarizers, and specialty filters like IR-pass. The purpose of a camera in digital capture is to capture as much data as possible for rendering, which is a matter of exposure control rather than tonal/color adjustment, and the vast majority of creative control is in the image rendering process after the fact of capture.
Keeping in mind the characteristics of the entire imaging process leads to the best use of filters and other techniques.
BTW, I only rarely fit any filter for "protection" purposes. Only in driving rain, in blowing grit and sand, in flying mud and other miserable circumstances when maximum image quality is impossible anyway do I use a clear glass filter to protect a lens from the elements. A rigid lens hood, bayonetted or screwed into the front bezel of the lens, is far better protection and minimizes flare rather than increases it.