I've had this issue come up in big Fates like Svara and Lazy Laurence. But even despite not being able to lay down dots and fester, I've still come out with Gold in those cases, and usually I wasn't even in a party. (I have more baby buns than I know what to do with!) If you're not dealing damage, Arcanist/summoner is a good second healer.

That said, I do think the cap is a bad idea, though. Wouldn't mind seeing it lifted.