They took themselves seriously (as did everyone else) because they were seriously ****ing good.
I don’t particularly like looking at them and would happily accept they may well have been a bunch of ****s (that said, Robert Plant these days seems a very nice chap). Its just inconvenient that the music is extraordinarily ****ing good. To write it off as souped up blues is ridiculous as anyone who has made it past Zep 2 will know.
Anyway….. each to their own and all that.