MIG wrote:

Touching at the platform readers is only necessary when changing to or
from National Rail from or to either Central or DLR (and then only NR
east of Stratford?).

I was told one had to always specifically touch in and out for the DLR,
hence the tunnel readers at Bank.

National Rail services west of Stratford only go to Liverpool Street and
this section is covered by Oyster.

But because that's deemed too complicated to
understand, one is encouraged to keep on and on touching at every
reader one passes, putting one at risk of potential unresolved
journeys.

Indeed - hence the mass confusion.