It is an urban legend. "Dedicated line"'s original meaning is to have a line that guarantees for 99% or the like of time to provide full throughput of the promised bandwidth. A truly expensive service for businesses etc.. None of the usual consumer subscriptions of any provider operating on the fiber networks of the cities like Zürich, Basel, Bern etc. do provide this. They are just "best effort" like everyone else including init7.
A bad joke at best.