Their entire club ethos is built on confidence and momentum. If they win that game then their whole playing squad, manager, and fan base are swaggering into the Spurs game like they’re the best team in the world again, the media are lapping it all up once again, and the likes of Dier Sissoko Bergwijn and Ben Davies have already started having a few nightmares about the game. They get back on a roll and that is dangerous. Klopp then throws the next round in the cup anyway by putting the kids out.
So really the only slight ‘benefit’ they’ve gained is United have a few extra games. But all the confidence is now with United and Liverpool are again facing introspection and criticism as more doubt will seek into that squad. If it’s right v Spurs and there’s anything that makes them try and hold on for a draw than press for a win then that’s a good thing. It’s far better to completely undermine the self anointed ‘mentality monsters’ rather than letting them get back into that mindset.