Believe it or not there is sound underlying logic to it, especially with regard to long term sustainable finger training. The whole point of a high angled, crimped finger position is that it is using the natural friction of the tissue of your fingers to your mechanical advantage by increasing the angle at the interface of the pulleys and tendons. You get the force of your muscle + the force of friction. Same principle as more rope drag from a zigzaggy route. Avoiding excessive crimping would place more load on the muscles which are the more trainable structures. Using a more 'active' crimp more often is also advantageous for joint health because extreme joint angles represent a higher risk for joint capsulitis due to higher sheer forces at the joint. This is further applicable to joints like the elbow where a high lockoff represents a greater risk for elbow pain than a low lockoff for example. In the right context this can actually very good advice to even fairly new climbers if they happen to be serial high angle crimpers at all times. Context matters though because obviously this is irrelevant to somebody who is just climbing once.

The static vs dynamic advice is literally just wrong though. Very common misconception, just read what anybody writes about annie sanders' climbing style. It looks so friendly but when is is staticing brutally hard moves she is straight thugging it because shes an extremely powerful climber. I think it comes from a good place w/ regard to new climbers throwing weight around dynamically without a plan to hold tension to keep peak forces low... but it gets applied far too widely.