The graph in that page illustrates exactly what I'm saying though only to a tiny extent but that's because it's the graph for the very best films out there in terms of reciprocity performance. If you draw that graph for Fomapan or an Efke/Adox film, you'll see a big sweep upwards. The change in contrast is a function of the fact that as the light intensity reduces, the film's effective speed wrt that light reduces.

Consider a bright-night shot (with 5-stop range, ought to just fit OK in a print) on Fomapan, 2s indicated exposure. Bright parts (Zone VIII) would have a light level implying a 0.25s exposure for Zone V and therefore no reciprocity failure while dark parts (Zone III) would meter at 8s. At that lower light level, a 3-stop reciprocity correction is required, so what should have been nicely textured shadows at Zone III have now dropped off to completely blank (if you don't do the reciprocity-failure correction). If you apply the 3-stop reciprocity correction for the shadows, they're back at Zone III as desired but your midtones (that only required a 1-stop correction) are now up at Zone VII and your highlights are 3 stops off the scale and completely blown. Net effect: get a huge N+3 expansion just from reciprocity failure in a typical scene, without changing development at all.

Solution: don't use old-style film for night shots unless you want to go even longer than indicated and then pull development and cross lots of fingers and toes.

Sure, if you do the test with Acros or TMY2 (edit: or Provia 100F) you will see no difference in contrast at all but they have practically no reciprocity failure whatsoever as evidenced by your link. That is the major reason I love those new films - I can go out at night and just shoot without having to worry about my shadow detail evaporating. And I can do a 10- or 20- minute exposure without having to correct anything (well, maybe half a stop for TMY2) and it will still have the same contrast, whereas an older film would be completely blank.

(this is not me beating on old-style emulsions; I absolutely love Efke-25/CHS-25 but I would never use it for a long exposure)