See Dependency Hell. This is when you tried to install something (Red hat linux Package Manager) using an RPM, and then it turned out you needed another RPM as a prerequisite. After downloading that, it turned out it needed another RPM. And so on. Modern versions of Linux use fairly sophisticated package management system to deal with this so the user doesn't have to.
While there is a certain romanticism to digging into the guts of the system and doing all the work yourself that goes (went?) with Linux, I think everyone will agree that RPM Hell is something that nobody feels nostalgic about.