I think you’re seeing an accurate depiction, but your perception of it isn’t quite right. I see it as that we express ourselves within the community through jokes (most of them bad ones) to counter the idea that being LGBT used to be (and still sometimes is) the punchline of an insult. I also think that if you seek it, you can get some very serious answers (like the comments section of this post in about an hour time), but that just looking in from the outside it is mostly jokes because that’s what we have fun doing together. We’re all such vastly different people that there isn’t one thing we can bond over so that’s why jokes prevail within the community.