Cue Morgan Freeman being beaten by a flashlight

I'm not OP, but the Maglite was originally developed for use by American police in the late 1970s. They made it long and heavy so that it could be used as a club (sorry, "impact tool"). Like most things that the police did during that time, these were mostly purchased with the intent of providing plausible deniability about racial profiling and police brutality (and if they weren't purchased with that intent, they were often used for that purpose anyway).

Large maglight-style flashlights like that were often carried by people who weren't permitted to carry a truncheon/nightstick, as a big stick full of D cell batteries is an extremely effective club (until it bends). While the idea that mostly people who owned them used them to beat black people is a bit hyperbolic (for a long time they were just the most reliable flashlight you could get) they definitely were also used as a bludgeon. Mostly that role has now been filled by telescoping batons though, just as effective but much less weight to carry around.

They were very popular among security guards that weren't supposed to be carrying a weapon.

Maglite flashlights are big, heavy and durable and are usually standard issue to police. They make for very effective bludgeons which cops have clearly rarely had qualms about beating black people.