Been looking through the archives for a good method of making sliding doors and cmae across this FWW article by Seth Janosky.  

https://www.finewoodworking.com/SkillsAndTechniques/SkillsAndTechniquesPDF.aspx?id=2937

In it he states

“Doors run much more smoothly when they do not actually rest on the bottom of the grooves in the lower track, but rather
on a small ledge. This is achieved by adding a rabbet at the top and bottom of the door, leaving thick tongues at those locations,
and then cutting the grooves to fit the tongues. I usually place this rabbet along the front edge of the door, though most Japanese cabinet doors have this ledge along the back. The tongue does not bottom out in the lower grooves, leaving a
gap for crud to gather without derailing the door or scarring the wood.”

My question on this is wouldn’t there be obvious marring of cabinet bottom from these front door ledges sliding back and forth?

thanks for any and all replies.