Trilarion: Actually it's not that important if a restriction is technical or legal.
timppu: Of course it is. If I want to play a game I buy today in 10-15 years, a technical restriction (=DRM) may well make it impossible for me to play the game even on the same system it was bought for, e.g. if it requires connection to an authentication server that does not exist anymore. A legal restriction will not, especially if the publisher/rights owner has gone bankrupt long time ago.
I have lots of 10-15 years old PC games that I still intend to play. If any of them required any online authentication now, I'd be pissed off. The closest case was Dune 2000 where I tried to update the game with the ingame "online update". Of course it didn't work, Westwood's update server hasn't probably been running for many many years. Fortunately I found an offline patch for the game.
Why is it not a problem for you, when there is a legal issue? Maybe because you don't give a damn about legal issues? Maybe because you think they are easier to circumvent? But then copy protection (the technical side of DRM) is also easy to circumvent. In many cases pirated versions are ready to download. Only the existence of a game server might be seen as a technical limitation, but then eg. WoW would be a single technical limitation.
I would say, that as long as somebody doesn't want to do anything illegal, then a restriction is simply a restriction, doesn't really matter where it comes from.
Here is my approach to solve this question once and forever:
1. We drop the D from DRM, because this is not general enough. Hence we have RM.
2. We replace the M in RM by R for Restrictions, because Management is kind of an euphemism.
3. We end up with Right Restrictions (RR) and sum up all technical limitations or legal clauses, that disallow any of the following:
- reselling the game legally including officially transfer of owner rights at no additional costs
- letting the game run, install (repeatedly) without any third party (apart from OS) action, especially among no account checks and on unlimited computers
- no artifical time limit on running the game (except OS compatibility)
- multi player: obligation to open any server code upon going out of business so that operation can continue
- in short: anything but the minimal necessary technical and legal limitation for running the programm and treating it like property
In this way, almost everything becomes DRM including famous GOG, except DRM free stuff sold on physical media or DRM free downloads that allow transfer of games between accounts and do not forbid reselling (which is technically not a big problem).