I wonder if Eul had any influence in this...
Anyways, I was sure from the start that Valve will kick the greedy blizz's ass in this "battle." And the "war"? That's already won by Valve cause Dota2 > Bliz All-Stars.
btw, don't get me wrong. I was a fan of blizzard until they screwed warcraft with wow.
What is up with everyone hating on wow? I haven't played that game since earlyish vanilla, but tbh it was being developed before WC3 was released, and while it currently may have fucked up the story (which wasn't excellent to begin with), it was leaps and bounds above any other MMO back in the day.
Eul probably had some influence. But the thing is, had they gone to court to fight over this, they would have had to start questioning their own EULAs and their legality. That could be interesting, since all these software companies have started to claim dictatorship á la Germany 1940ish over their own products and how you can use them.
For example, you can mod an XBOX console. The only bigger drawback is that you would break the EULA (or TOS) of XBOX LIVE if you go there with a modded console. If the console was forced to use XBOX LIVE, modding it in a worthwhile way would be troublesome.
By enforcing everyone who wants to use the product to use the service as well, you can truly enforce your IP rights. There was a threat that a case like this (concerning modding and such) would endanger this current stand on these issues.
Blizzard has already done this with Battle.net 2.0, Valve has been more lenient on it's behalf - however, steam licenses state the same thing. The companies want to secure their own rights to their games - even Valve doesn't necessarily want a modded game which heavily uses their assets, to spawn into another game on which they have no power or control on. Played on platforms from which you can make no money from.
How far the companies will go with their enforced rights, is another matter. Blizzard are the greediest ones here, trying to control over the whole scene, including tournaments. They have presumeably gone a bit more easy on this, now that SC2 wasn't exactly as succesful as it could've been - BW wasn't dethroned.