If you can use duplex breakers, is there ever a reason not to?

In general, when circuits need AFCI protection (or GFCI protection if you don't feed everything through GFCI receptacles), you can't use duplex breakers, since there's not enough room for the protection circuitry. However, when they don't, is there any reason not to use as many duplex breakers (or quadplex breakers if MWBC's are involved) as your panel will let you? In other words, is there ever a reason to use a normal single-pole breaker when your panel can still take more duplexes? I ask because I read here a lot that panel space is precious, but I also see a lot of normal single-pole breakers that could be duplexes.