I've noticed that too. To me, it's a problem for our reviewer/requestor licensed people who aren't super familiar with Workfront. I've had a few ask me, "Why didn't you get my response?"
If the user replies directly to the email, it goes to noreply@attask.com, which is an email address that none of us monitor (or have access to).
We do not receive their reply.
There is also no communication sent to sender that their reply was not received.
I don't have any measure on how big of a problem this is, but I do believe it is a risk.
POTENTIAL SOLUTION: According to this Workfront support procedure (