One of the interesting insights into society at large is that one of the big divisions of knowledge is into the pots of "benefits others that you know this" and "other". There is a lot of social effort put into spreading political memes (as the easiest example) because that will influence society in a way that is favourable to the meme-er. Ditto a lot of commercially useful skills are spread because it is in everyone's interests that businessmen are competent. Messages of peace, kindness and (ironically) war get a lot of play because they are all helpful in various ways if other people know about them.
Reading up on the jhanas they are clearly a very real, very distinct thing. But they aren't obviously to the benefit of anyone except the practitioner and it is practically impossible to verify if someone has actually experienced them. So they drop out of the conversation pretty quickly unless they are attached to something else (this is a large part of the genius of Buddhism and other religions, attaching good ideas to social rites).