Hello Hathor. We reply through email for lots of reasons but mainly because it's a system the MNHQ Community team can all access.
So, if you report something while I'm on duty, I'll reply. Then if you reply back later, when someone else is on duty, the new duty person will be able to see the correspondence and get back to you.
If it was all done by PM, I'd be PMing you; you'd PM with me with your reply - but I may not see your reply till my next duty shift. Which could be some time...