Average time played is not a good metric because people on both extremes will skew it heavily, like any average - people who bought the game but never played it, or people who play it way too much. It also depends a lot on the game. On an okay-ish game that has a +/-20h campaign will be pretty easy to munch through just to check it off, but one can easily abandon an okay-ish game with 5-10 minute matches after a handful of hours.
I understand the point you are making in regards to average time played, but surely the people who, quote-unquote, play the game way too much, enjoy that specific game very much? Please note that you can also see the median playtime on the abovementioned website.
Is that a common practice? I once accidentally bought a "standard" version of a game instead of the "ultimate" on my Xbox One and had to deal with a couple of support people to refund my original purchase in order to get the other.