Sure thing.

Regardless of the reason, Valve seemed to change their opinion of Sony/PS3 sometime after the Slim released. Before they despised the PS3. Afterwards, they said they loved it. Doesn't really matter why. 

So what was your reason for this being a 360/X1 exclusive, you never really said.

Just checked, and apparently they didn't want to develop for Ps3 because their first effort (The Orange Box) was a shoddy port, and they were accused of being lazy developers.

Years later, they gave Ps3 players the best version of Portal 2.

D:

I never gave a reason. I, in fact, said that I can picture Left 4 Dead 3 being on Ps3/Ps4. I just called it! I don't think Valve will give Ps players the third entry of a franchise without the other two, unless they're planning to give them all.

By the way, The orange Box had only sold about 6-700k when they began development for L4D2. So the fanbase from that game wouldn't really be big, especially considering it was a notoriously horrible port handled by EA.

I'm actually surprised by how few "count to three" jokes there have been...

Well there have been other circumstances where this has occures, although it was not with Valve.  Ex. Mass Effect 3 was on Wii U with the first and second ones being absent.  I think they would want to put it on as many consoles, that are profitable, as then can.

Yes, but that was seriously screwing from EA, since they didn't have any real motive for not releasing the Trilogy as they did with the Xbox and Ps3 version (On which the Ps3 finally got Mass Effect 1).

Left 4 Dead 3 will be on PS4, 100%. You don't need to play L4D1 and 2 to 'get it' either, there is basically no story.