Are Derailleur Guards worthwhile for kids?

[Mububban]

My kids have just graduated to 1x7 bikes, and inevitably they're going to drop it on the derailleur side eventually.

Do those metal loop derailleur guards I see on some kids bikes offer any worthwhile protection or are they largely cosmetic? I'm talking a 6 and 8 year old dropping it when getting off, or a low speed crash. They're not doing huge jumps or attacking downhill trails

[bychosis]

I wouldn't buy one, but wouldn't remove it if fitted. My kids first 20" 1x7 had one, but three other bikes (2 24" and another 20") haven't had one and have survived.