Do you have consistent gaps between all your teeth, and/or other conditions like strong enamel, or a good diet? If so, congratulations - flossing might not do much for you. But it's ridiculous to suggest that - if you don't floss and get food stuck between your teeth for days on end - that doesn't have a negative effect. Arguments about correlation/causation be damned.

> Starting a flossing regimen after not having one tends to cause pain--isn't that a signal to stop?

Moderate exercise after not exercising for a while causes pain - is that a signal to stop?