For the same reason some kids wrote their names on card backs or three hole punched comics…Because we were stupid kids…
Yes, anyone who has accumulated major amounts of OS stickers from purchasing full collections, miscellaneous lots, etc has undoubtedly also acquired a subset of stickers with these issues - initials or names on back (always in ink of course), peeled borders, re-sticks, etc. a shame, but it is what it is. The sheer population of surviving stickers in collectors hands still blows my mind, so have to be grateful.
I have seen one or two hold-punched comics over the years, but thankfully I never did that to mine. Did manage to somehow lose some of my childhood comics, but what else is new.
