When you mainly play non-current generation games, as I do, you are pretty much required to have a "backlog". Although, I wouldn't call it a backlog exactly. I'd say it is acquiring games for future use.
People like me benefit from acquiring older games in batches, to get deals and save on shipping. Also, the prices of 8/16 bit Nintendo games has been consistently rising since 2009, with a huge spike in the last year or so. I "saved" a lot of money by purchasing almost all of my games before the bubble. While you could argue that the money invested in games sitting on my shelf for two years could have been put to better use, I would have undoubtedly spent more if I had simply bought each game as I felt the desire to play it.
During the PS2 era, I did have a legitimate backlog. I would continue to buy new games as they went on sale, despite hardly playing the ones I already owned. I quickly saw my mistake and sold off my PS2 collection to focus on older games I had missed along the way.
I wonder when the concept of having a backlog of games needing to be played came about. It certainly did not exist in the 80s and 90s. We simply had games we actively played, and games we used to play. Even games that were not very good saw play, because we didn't own many games and had to enjoy what we did own. Renting was so prevalent that we didn't feel the need to buy everything, and even bad games would get one play-through before being returned.