The airline has a responsibility to get you to your destination. If your flight is cancelled or you miss a connection due to a delay (with flights on the same ticket) they have to make (and pay for) alternative arrangements.
But what about stopovers? are they required to provide transport to your stopover location? or only to your final destination?
This is potentially significant because as pointed out in this answer, the "destination" from a ticketing point of view may not be the same as what the traveller thinks of as their main destination.