It’s become more common with FastMag “pouches” (or whatever the hell they are, they’re plastic). There’s a federal agency who's “special tactics” unit seems to do it as a matter of organizational SOP, just can’t remember who off the top of my head.
That said, those look like your standard, run of the mill el cheapo loosey goosey nylon mag pouches with a retention bungee. Those bungees slide around all the time. I wouldn’t have very much confidence those mags would still be there after a spirited foot pursuit or rolling around in the dirt with some dude who has a bracelet allergy.