They switched from coin to paper/linen in the past because paper was so much more convenient (lighter, takes up less room, can be folded).
Their goal here (and the goal of other nations banning higher denominations) is to force — eventually — people to carry their cash in 1’s and 5’s.
The idea is that people will get so fed up have having huge wads of smaller bills that they’ll demand that their governments “offer” the alternative of digital currency.
The governments will be happy to oblige, since that is their ultimate objective.
Once it is available as an alternative, they’ll phase out non-digital currencies completely.
Then they’ll be able to monitor your every transaction and shut down all of your buying/selling activities should they deem you not to be “in compliance” with whatever they dictate.
See #29.