Valve is definitely gaining grounds when it comes to creating multiplayer online games like Dota 2 but they seem to have been ignoring their single player fans and the fans are getting tired of it.
We know that Valve knows what makes a great single player game but the problem with them is that they just can’t seem to get the games out. Fans of Half-Life have been waiting for them to release the third installment for more than 10 years now and it does not seem like we are close to getting it. The Portal fans are also waiting for Valve to release a Portal 3 game but Valve has never indicated that they are working on one right now.
One of the reasons why the fans think that the Portal 3 was part of Valve plan was because of the ending in the last game where Chell was seen in a field with a companion cube.
If Valve continues to ignore their fans, there will eventually be a day when the fans will just turn their back on them and there will be nothing they can do about it.