There's no person who judges a man harder than that man himself.
I'm sure they are very aware of their circumstances. What your teammate is trying to say is that it's about par for the course to see people who are tilted die more trying to get back into the game. The best way to combat the feeding is to realize that they're dying repeatedly like that because they're in desperation mode. They're tilted, they want to get back into the game, and they think the only way to manage that is to try harder in a situation that they're not set up for.
You need to help them to untilt - the best way to do that is to remain passive about the scores, and try to make some indirect shotcalls. For example: if your ADC is the one getting rolled, try and have them farm at top instead. If it's your jungler, see if they can't camp the laner who's doing well, and snowball them a bit, so it gives them more room to farm without worry. LIGHTLY guide them - don't try and take command, but give suggestions like "cover top for a sec please?" instead of something like "farm top, I'll fight the fed guy."
One is a suggestion to have them cover for you and it helps them feel like they're being useful in getting to an area you're unable to reach in time (even if you easily could have. :P). The other is more "get the fuck out of the way, I'll handle your mess" and feels more demeaning.
It's one thing to know how to play the game. It's another to execute it.
And it's a whole new way of playing when you realize how to heal tilt instead of adding additional tilt when your teammates know part one but failed part two.