I think that some MIRI researchers, or at least active community members, originally encountered the LW/MIRI memeplex through HPMoR.

Also, I met someone who said he was formerly very religious and is now an atheist. He said that he was brought into the LW world through HPMoR and HPMoR seemed to still be the main focus of his interests inside this memeplex. Though I can't say that HPMoR was the only cause of his shift of attitudes or even the main one, it apparently had an important role..

So, it does seem that HPMoR has some strong effects on some people.