There are lots of video gaming forums already. The world doesn't need yet another. Creating an Arqade-branded forum would be putting a massive amount of work into creating something that nobody needs.
Or, put another way:
But what about just using chat?
As a standard practice it wouldn't work. The feature set of chat just doesn't support this use.
The occasional attempt to do so might work, but those would be the lucky exceptions, not the rule, and most people we sent to chat for their questions would be disappointed (and possibly feel mislead).
Most of the reasons it wouldn't work come back to the fact that chat's design is tailored to serve its official purpose. A thriving forum needs a different design.
For reference, the official purpose of chat is to be an
informal public gathering third place — a space for people who love the topic to meet, discuss, and collaborate in a different way. It would foster community, and be complementary to both strict Q&A;, and meta-discussion.
Chat's features are optimised for making it a place to hang out and socialise and discuss with fellow enthusiasts about a site's topic. Though it could be (attempted to be) used for overflow questions that are off topic, too broad, or primarily opinion-based, most such attempts would be strangled by the lack of infrastructure supporting them.
Chat rooms aren't indexed by search engines for their titles like Q&A posts are; the chat site's design doesn't encourage browsing the list of rooms; chatrooms aren't exposed elsewhere than that rarely-browsed list, making new ones easy to never notice; message activity notices for them don't exist on-site (you'd have to set up a personal RSS notification with external software); chat has a much, much lower level of traffic than the main site does; — just for a few anti-features that I can think of off the top of my head.
Chat just isn't designed for being a discussion forum instead of chat. Sending people there with the promise that they'd get satisfaction for their discussion topics would be making promises that the software's design won't keep.
(You can do an experiment right now to see this in action. Pick a question that has one of those reasons from the list of closed questions and make a new chat room with its title for a name, and turn its body into the first message. Then observe whether it gets any traction.)