I feel like most places eg. websites, subredits, facebook groups ect ect that are there specifically to promote your YT channel are usually a dead end, Unless you have a very niche group (for example... Art videos, or food review videos ect) there's no way you're going to get any traction because the only people that actually GO on the website (ect) are there to ditch a link and leave.. 99% don't care about other peoples content, the same way the other people don't care about theirs...
Places like this forum are good because, sure, if you're active, people might check out your channel if they're interested and you might make new friends, but you're never going to pull a huge audience from anywhere designed FOR content creators..
Kinda makes sense though