Makes sense for Appys that have little hair. I am used to horse with a LOT of tail though (Foxtrotters, Walkers, drafts, etc), so I never used extensions. Often I would just braid the tail to make it more manageable, or at least out of the way for lessons (or as a whip for the horses to smack the trainer with hehehe).
Yes, It works well for my appy. My POA has a super long tail to the ground, so sometimes I put them in and braid them. My quarter horse has a decent tail too, so I have to put longer pieces in. I guess im silly because I don't have any kids to dress up LOL. So I play dress up my barbie dream horse haha. Maybe I just played with too many my little ponies as a child, consequence of being an 80s kid!
I'm used to one of the ladies at my barn, who has 4 little girls, who like to dress up their halflinger pony. I've seen some strange stuff for that poor boy lol. He is very tolerant though, especially of the blue sparkly hoof paint.
He has a ton of hair (double mane and tail sort of hair) so no extensions for him.