yes.(● ̄(エ) ̄●)
While there are stories that are intended to focus on the romantic relationship aspect, Yaoi does have the purpose you stated. It seems as though people forget that Yaoi is a form of porn, and that's probably because those who read it for the first time are like middle schoolers or something, which omg they really shouldn't be. But yeah, Yaoi can be a type of porn and can be intended to stimulate arousal.
Okay Ive got a very very weird question and some of yous would probs think "wtf is wrong with this bitch?" Anyways Im still gonna ask this question
Have any of yous masturbated while reading a yaoi, ecchi or any of the adult genre mangas before? Yeah its a weird question but hey you dont have to answer it if you dont want to ╮( ̄▽ ̄)╭