Bethesda introduced DLCs to the PC gaming world in 2006:
http://en.wikipedia.org/wiki/The_Elder_Scrolls_IV:_Oblivion#... The first update came as a set of specialized armor for
Oblivion 's ridable horses; released on April 3, 2006.
Although gamers generally displayed enthusiasm for the
concept of micropayments for downloadable in-game content,
many expressed their dissatisfaction at the price they
had to pay for the relatively minor horse-armor package
on the Internet and elsewhere.[85] Hines assured the
press that Bethesda was not going to respond rashly to
customer criticism.
Valve introduced DRM to the PC gaming world in late 2004:
http://en.wikipedia.org/wiki/Steam_(software)#History Valve's Half-Life 2 was the first game to require
installation of the Steam client to play, even for retail
copies. This decision was met with concerns about
software ownership, software requirements, and issues
with overloaded servers demonstrated previously by the
Counter-Strike rollout. During this time users faced
multiple issues attempting to play the game.
There are alternatives like GoG, that are DRM/DLC-free.