I don't know how someone could look at the plaque buildup that you scrap out of between your teeth and decide that it's not bad, because there isn't enough evidence to say it's bad.
I didn't floss for the longest time. Then a few years back when I went on my diet I also decided to start flossing regularly (daily before brushing my teeth at night). My gums no longer bleed at all when at the dentist and they poke around in there. Also I'm pretty sure my breath must smell better. If I go a day without flossing, then floss, the plaque that comes out with the floss has a very bad smell. I can't imagine having that stuff sit in between my teeth for days.
____________________________
Can't sleep, clown will eat me.