I think they restrict the 2FA methods since they want tighter control over them. For example, if you use their Steam app for 2FA and you need to move it to a new phone your account gets put into a restricted mode and you cannot use the Community Market for 15 days. This restriction also gets applied to any item you touch, so if you trade an item to someone else, the store restriction moves with the item.
They also strong-arm you into using the app. If you log into a new device (or Steam thinks it's a new device since you cleared cookies) and you don't use their app for 2FA, then the device will not be able to trade or use the market for 7 days. They only waive this restriction if you use their app for 2FA and it has been active for at least 7 days.
It's a bit frustrating since the Community Market/Trading is likely only used by a minority of users, but seemingly a ton of login limitations are imposed because of it.
> It's a bit frustrating since the Community Market/Trading is likely only used by a minority of users, but seemingly a ton of login limitations are imposed because of it.
It's probably because it moves a significant amount of money, between trading cards, CSGO knives, TF2 hats, etc. Of course, nothing comparable to banking systems and general-purpose marketplaces, but I personally think those protections only add to the product.
> Of course, nothing comparable to banking systems and general-purpose marketplaces
Rumor is, some MMO games have markets exceeding GDPs of plenty of first-world countries, and ingame items are used by gangs to move funds across borders. Both Cory Doctorow and Neil Stephenson wrote books featuring this phenomenon, and I'm pretty sure they both usually take their ideas from reality.
Since Steam is a Big Guy, and its market is dedicated to this very activity and sits on top of many games at once, I'd guess it to have a sizeable slice.
Doctorow's book is “For The Win” (if I'm not mistaken—really need to get into the habit of writing some notes about the books I read, especially when marathoning through an author's bibliography).
Stephenson's book is “Reamde”, which is a weird, even for him, mix of realistic-sci-fi-about-computers with an adventure thriller.
I think I also found some articles about actual size of virtual economies and the use of them by crime. But those likely went into the Pile To Read, which is a rather sad fate in my case and the hope is thin.
I don't use the Steam 2FA app and when I sell Steam trading card, there's a banner saying 'you haven't used our 2FA, market listing will be held for 7 days'. But then usually the cards I list are sold the same day, I don't really understand why; perhaps because (on the Steam client), I rarely have to log in?
They also strong-arm you into using the app. If you log into a new device (or Steam thinks it's a new device since you cleared cookies) and you don't use their app for 2FA, then the device will not be able to trade or use the market for 7 days. They only waive this restriction if you use their app for 2FA and it has been active for at least 7 days.
It's a bit frustrating since the Community Market/Trading is likely only used by a minority of users, but seemingly a ton of login limitations are imposed because of it.