'My personal failure was being stumped': Gabe Newell says finishing Half-Life 2: Episode 3 just to conclude the story would've been 'copping out of [Valve's] obligation to gamers'
They hoped the episodic delivery of games would be the future. Especially alongside a digital distribution platform like Steam. I suspect they realized episodes wasn’t the way after the release of Orange Box, so they moved on from that.
Valve buys up dev teams that are about to shake the industry up. Valve haven't actually been the ones to make something new in a long time. TFC, CS, Portal, DoD, L4D, Alien Swarm, Dota 2... were all made by outside dev teams that Valve absorbed and put their name on. The only things Valve have actually made, themselves, in the last 5 years are Alyx and CS2, neither of which brought anything new to the industry (although they are wonderfully-executed games) and are both sequels of existing franchises.
Personally, I'm not a fan of this practice, because I feel like Valve inadvertently stifles these studios after they bring them onboard. For instance, the team from DigiPen that Valve bought for their Portal tech? Imagine if they were still able to make games. Imagine if they were still able to stretch their creativity and create new tech and ideas. Instead, their intellectual properties are all tied up at Valve and they got to release two whole games in the last 20 years. Who knows what we could be missing out on from these guys if they were able to actually still make stuff.
I wish they didn't feel this pressure to push forward the industry with EP3. Full Half Life 3, maybe, but I would have preferred a closing chapter with the tech and features available.