Hiking near Asheville made me finally see the root crown on old oaks

I was doing a trail cleanup after that storm last spring and stopped to eat lunch under this massive white oak. Stared at the base for like 10 minutes while chewing a sandwich. That flare where the trunk meets the dirt, I always knew it mattered for stability but I never really looked at how the roots spread out from it. Then I walked around and found three other oaks on that same ridge where someone had piled mulch up against the trunk like a volcano. You could see the bark rotting at the root crown line. I've done maybe 300 tree jobs over the years and I never once flagged that on a risk assessment. Now I check the root collar on every removal bid and I tell homeowners to keep mulch 6 inches away from the base. Has anyone else caught themselves overthinking a tree's buttress roots after just sitting there and looking at one for a while?