Well, the exceptions are not that exceptional. Do you buy digital music that you cannot lend? Are you not able to lend a game purchased on gog without paying? All the ebooks I bought I share with my family (and I have the legal right to do so, admittedly, I live in a country where DRMed ebooks are not the only solution).
I don't get this entitled view people have on creative content they purchase. Yes, you certainly own the content in the sense that you can now consume it and enjoy it forever. No, you cannot go and take this content and essentially sell it for $0 to everyone because it's now in your possession.
I have always shared some books with my family, and I continue to do so with ebooks. It also happened that I watched DVDs with my family or with friends. This is legal and this is totally reasonable use. And I am entitled to share and copy creative content with my family (close circle) by the law of my country as long as I do not break copy protection, which is why I do not buy DRMed goods.
You can't have a purely digital content item and not have it bind itself to some kind of purchaser. Why? Because then you'll have one person buying the item and distributing it for every family and friend out there. You might then try to argue that physical items like books and DVDs are subject to this exploitation. Obviously the physicality of the items make them unfit for mass sharing. It takes a lot of time to swap around a single book or DVD. It takes 5 seconds to whip up a dropbox link to my giant email list.
Aside from the above, Steam started off with a "all sales are final and permanently tied to the account purchaser" model. No one expects to be able to buy a game on Steam and then share it with a friend.