Some WP Forum users…
Of course, this most likely will also be true for many many other forums, in which help is sought/given. However I’m ranting from my view when going through the Wordpress.org forums, so it’s obviously Wordpress based, and maybe also biased 
Wordpress Forums offer a few subforums, such as How-To and Troubleshooting, Plugins and Hacks, WP-Advanced, and more. These three are those I browse, with preference in the Plugins and Hacks forum, to keep an eye on updates or issues with plugins I use. It is fairly well visited, while How-To and Troubleshooting is the most frequented forum of all, judging by the amount of topics in there (almost three times as much as the 2nd largest forum, Plugins and Hacks, ca. 141k topics vs. 55.7k topics at the time of writing).