I am member of a couple of Matrix rooms, incl HPR. Matrix is a good place for talking. 

I think the direction is that a person first knows about HPR and then join HPR Matrix room. 

But my interpretation of the idea to use Discord is the opposite direction: Persons not knowing about HPR should learn and get interested in HPR thanks to learning about it on Discord. I have never, to my knowledge, used Discord. So I do not know how Discord works or if the idea makes sense, but this is my understanding of the Discord suggestion.