DBM isn't required to raid. Competence is.
However, for those players that are incompetent, you should ask them to run GTFO addon instead. Seriously, the only thing that addon doesnt do is get you the fuck out.
Yeah in what, heroics? You're a liar if you're trying to say that you manually count timers for phase changes while keeping track of more than two enemy health bars, enrages, and global abilities from bosses. Boss mods aren't for incompetent players, they're for GOOD players who want more awareness available to focus on other aspects of the fight, like knowing when adds spawn and precasting, keeping procs up before RP event fights start/phase changes, min/maxing their rotations, and when they're going to take lots of damage to use cooldowns, healthstones, whatever is available to them.
Get your elitist shit out of here, you're a terrible, terrible player if you honestly believe "boss mods aren't necessary" on any form of current or upcoming progression content. Why do you think guilds MAKE them as they progress through new bosses? Maybe not if you're doing normal modes and want subpar dps and reaction times. You don't rely on them to tell you what to do, you use them to maximize your ability on that fight.