I think the other reply is referring to folks who collect and sell old magazines. I can only speak from second-hand experience, though, as I knew a person who used to do this. When eBay was just getting started, she was collecting old magazines and trimming the ads from them, then selling them as a lower bulk collection (she also took jeans with holes in them, patched them with colorful fabric and resold them on early eBay but different story).
I don't know why this was a thing, but I remember her telling me she got the idea from a local library that preserved its periodicals, so maybe it started at libraries. Personally, were I to collect magazines, I would want the ads intact. Not because I love adverts (quite the opposite, actually), but my collector brain's notion of preserving a thing in its original state is at odds with the idea of removing the ads.
In libraries we don't get the ads cut out. But yeah most of the physical periodicals will be bound in yearly volumes. Much easier to deal with. It's disappearing now though, with most periodicals only being published digitally.
I don't know why this was a thing, but I remember her telling me she got the idea from a local library that preserved its periodicals, so maybe it started at libraries. Personally, were I to collect magazines, I would want the ads intact. Not because I love adverts (quite the opposite, actually), but my collector brain's notion of preserving a thing in its original state is at odds with the idea of removing the ads.