> Thinking that changing "rare tag I do not understand" into "common but meaningless tag" added any value.

(1) I am definitely not changing all shop=* tags that I do not understand into shop=yes.

In such cases I leave them alone (for example, from start of my list of exactly such values:
shop=grossery, shop=towing, shop=showroom, shop=salon, shop=garage,
shop=pond, shop=consignment...)

(2) It was change of rare meanigless tag into a more common meaningless tag with support into some QA tools allowing easier spotting and fixing it (maybe it still should be not done, but presenting it as changing tags while I know that I do not understand them is weird)