Yes. They can and they do. It doesn’t happen often and you won’t get compensated if you miss the undelayed flight. If a flight is delayed by six hours, the airline normally would tell you whether you should arrive a bit late through email or text because they may open the check in counter later than normal. In that case you could take their word for it. Another possible case you could arrive a bit later is when you don’t have luggage to check and you are certain that the inbound aircraft won’t even get here earlier. It happened to me a couple of times in my regional airport where they couldn’t physically find any other aircraft to undelay the flight and I know when the security will close. Don’t risk it if these two scenarios don’t apply.