> But I could more easily just use my GBP to directly buy Euros, with one less exchange rate and one less transaction in the process.

In this scenario, the transacting bank would need to have (or want) to have GBP for them to sell Euros. While I agree this is a poor example, think of the more obscure conversions. Swedish kronas to South African rands, etc.

Anyway, I won't pretend XRP is a perfect solution. Just seems to me that it solves the edge cases of liquidity while doing so more cost effectively, which in turn benefits the consumer.

Why wouldn't the bank just use dollars or Euros as the intermediate currency? Have a pile of dollars, a trading pair for everything against the dollar, and you're all set.