Without any fanfare, it appears that Rick has updated the London guidebook only a year after the previous version. It dropped about a month ago. I'm guessing it will address things like not needing the Oyster card anymore since the earlier book still pitches it. Available through all the usual means.
Not needing the Oyster card?
I still use an Oyster.
Yes, know I could use a tap CC or debit card….
However, MUCH rather loose an Oyster card than either of those.
The worst problem in the London Underground used to be with paper tickets in the barriers when people in front of you might take yours by mistake especially if their ticket was being retained as having no further validity. In two occasions people ahead of me walked off with my £3.5+k season ticket and I had to run after them to get it back. One thing that smart & contactless cards have eliminated.
Marco
You can still have paper tickets when a national rail journey involves crossing central London between terminals
You can put your Senior Railcard on the Oyster and get a 33% discount. Can't do that on a credit card. You can also put a Travelcard on it that coincides with the dates of your visit so that capped fares work to your advantage. Perhaps they will come up with a phone app with credit card linked that can do all this for you someday, but I haven't heard that they have done it yet.