Here's a few thoughts about how developers ask for and receive help. I would include the developer forums, SFSE, and I would also add a third: Trailblazer Community.
Salesforce Developer Forums
Once upon a time there was a developer forum. This was founded and continues to be run by Salesforce. It is what it is, as has been stated, a discussion-based forum to answer questions. It has a some degree of moderation by Salesforce, and it is also monitored officially by Salesforce developer support. If you have no other relationship with Salesforce, it is the only official developer support channel available. It is, by and large, a developer-only forum, although some Admins to come there, and there are many point-and-click questions due to the nature of Salesforce.
Then one day a few community members got the brilliant idea that there was enough of a unique purpose that a Q&A site run on StackExchange would work well for Salesforce. This is especially the case as StackOverflow is really primarily a general-purpose coding Q&A, and there's certainly a fair amount of non-coding questions mixed in with the coding ones anytime you need to resolve something with Salesforce. So those kind folks started up a beta for salesforce.stackexchange.com. Several thousands of questions and answers later, we had proven ourselves to be worthy of a full-fledged stack, and the rest is history. While there are Salesforce employees who participate here (myself included), there is no official support for this channel, and all moderation is performed by the community. Salesforce tries to let this channel remain independent of any Salesforce influence (apart from the odd branding question now and again). Occasionally, to ensure there is good content in this site, we at Salesforce proactively communicate about things with salesforce.stackexchange.com, such as the recent LWC launch.
A third, and less well known place for developers to ask questions is the Trailblazer community. While I suspect adoption of TBC is a lot lower amongst developers than Admins, and it is not really used as a general purpose Q&A channel, it is often used as a way for product teams to officially communicate with developers about developer features. Lightning Platform team (Aura, LWC, ect.), Salesforce DX, APIs, and plenty of others have opened up Chatter groups in TBC to keep a more direct relationship with developers in the community.
I know of developers that use both, some developers prefer developer forums, and others SFSE. I think this is kind of a matter of taste at this point. Some people just don't dig StackExchange as a way to work. I have heard others express having been turned off by either StackOverflow or other StackExchange sites to the effect that they feel too burned to try this one. (I would argue that we're nicer here, at least I really sincerely hope we are!)
Whether you use SFSE or Forums, I would still recommend people get to know the product Chatter groups in TBC, or at least take a walk through there and see if any of the features you use a lot have teams there. Just as a for instance, there is a group for Lightning Components Development.