I'm reluctant to contribute an 'us and them' fantasy, but if there were a 'fixie'/'gearie?' divide, 'we' could take a look at our own sin quotient before launching stones....
How about cold-setting a 120mmOLN frame to 130 so you can use a modern hub/drivetrain? That is arguably mutilation more irreversible than cutting off hangers.. although to be fair there must also be frames about that have been 'fixed' by cold-setting inwards, too.. in/out/in/out...you know how that ends..
A comprehensive set of braze-ons is great if you're using them, but PITA if you're not... and there is
a sort of unhealthy authoritarian finality about them... someone decided for you that your gear-levers and bottle-cage and cables belong right here
... THERE IS NO ALTERNATIVE. Unlike clips, which left room for individual choice in component location, for better or worse.. Maybe I'm reading too much into this, but the subtle message of braze-ons could be interpreted as; "you are an idiot, let us decide for you", and a braze-on free bike says; "I don't know..it's up to you".
I personally dislike braze-ons on thin walled tubes, but if they have been put
there, then I want evidence that they have been
there, and the best way of ensuring that is to leave them there, but these days they could have been removed and replaced more than once.. remove/replace/remove/replace...you know how that ends... I can tolerate them better on stays, forks or lugs, where there is not so much potential for mischief..
If people are mutilating 'keepers' then that is their own business, but I agree that it's galling to find them back on the market afterwards. If there is a sharp distinction that needs to be made, it is not IMO between 'fixie' and derailleur/brake user, but between things to be used, and things to make a profit out of.. That would be welcome in all kinds of areas besides bikes.... housing, banking, transport, agriculture, you name it..... er, how did I get here from a mutilated Alan?