What are the pros of baby bottle liners if you don't have nipple liners too?

I need pre-sterilised bottles for a long haul flight, but can’t find any. So instead I’m thinking about using bottle liners… except, that still leaves me with the problem of dirty nipples.

So many of the liner reviews have mothers raving about not having to wash dirty bottles anymore… but what about nipples? I feel like I’m missing something, because if you’re going to wash the nipple, you may as well wash the bottle too, no?