The article is about IMST, which is strictly about muscle strengthening. This is maybe a side effect of the Wim Hoff Method, but the WHM also has other purposes because the main mechanism is hyper ventilation and breath holding. Here is good medical explanation of what happens when practicing the WMH (by a medical professional): https://www.youtube.com/watch?v=D6EPuUdIC1E (summary at 33:46).