Well if you've got a pile of ticket stubs that you've been collecting for 20 years and suddenly you can't keep that tradition alive, it kind of ticks you off. Sure you can start adding printed photos or something else, but it ruins your consistent collection and/or your streak.
I specifically have a ticket stub binder and seeing blank spots, or print outs or post it notes just made me mad instead of nostalgic. I can't shove tour posters or tshirts in there, so this was the solution for me. I have over 200 band tshirts, but I don't buy one at every show.
Never discount the power of a streak or continuing a tradition or collection. I just talked to a guy the other day whose jar of ticket stubs is his prized collection, even if he never opens it to reflect. Some people go to one concert every few years, others go to shows and games every week.
To go back to the GP post, why buy a fake ticket for this reason when you can print a real photo, buy official merch, etc.?