If you aren't getting injured, if you arent tired, if you are improving then don't take a day off.
I don't take a day off because I satisfy the above criteria. Also when I do take a complete daymoff I feel like shit and I even feel like I have lost fitness. 48 hours is a large span of time to do absolutely nothing.
The only thing that we truly know for a fact about running is that everyone is different. Do what feels right. Kara took zero days off after running Boston. Why don't we gather up all of your conservative friends and criticize her? We don't do we?
Josh cox takes a day off once a month, all the elites in Mammoth run twice a day, six days a week. And what do you think they do on the seventh day? They go and run 20 miles. And they are doing just fine.
Tell them you're happy taking days off works for them. But running seven days a week works for you and also makes you happy which as friends is what they should really care about.