no one has searched "the entirety of the internet" after you posted this less than 24 hours ago. you asked for examples and got 6. not every instance is going to be photographed and posted on the internet, and not every internet posting is going to be found in a basic search for "braze-on removal"

also, "rare" is a subjective term. at what point does a bike become "rare" or "valuable?" if there were 500 made? 5000? how nice does it have to be? what if it's just a nice centurion but it's in great condition because it was sitting in dad's garage for 30 years? if you are expecting 80 examples of colnogos and pinarellos under the knife, you aren't going to find it, but there are many, many NICE bikes that have been stripped of their hangers and braze-ons

i would also say that while the action itself may not be widespread, the THOUGHT of it is more commonly brought up than the action itself. i see WAAAAAAY more posts that say "i'm thinking of stripping the braze-ons off of this frame" and then people tell them not to than posts saying "i just stripped the braze-ons off of this frame" if you tell anyone who constantly stands in defense of something "i don't understand what you are so up in arms for, i don't see many examples of ____" they will probably reply "yeah, because we're doing our job"