I think a good way for me to explain the greatness of feathers is so kinda correlate it with my profession, massage therapy.
Imagine going to a massage appointment and someone immediately starts shoving an elbow into your back, off rip? It's not very fun, because your body isn't expecting any touch yet, let alone an elbow drop. That's why massage therapists will put a massage medium(oil, lotion, cream, etc) on their hands, and then apply it to the body, using a gentle pressure, just to get your body 'warmed up' and then you gradually apply more and more pressure till you hit the desired amount of pressure.
Feathers are very much the same thing. It's not meant to be the meat and potatoes of the tickling session, it's the way to get the body ready for the torment it's about to get. You CAN just immediately go into intense fingers into the ribs, but for me, I don't think that's as satisfying. You use the feathers to start getting their body ready. Difference is, gentle pressure in massage is welcome, gentle tickling is a bit harder to deal with because it's one of those "either tickle me or don't, but stop teasing me" scenarios. The gentle tickling seems more like a mental game vs just straight up physical. So I personally love feathers.
Not only that, but as a foot guy, myself, feathers are VERY effective on toes, I feel like with that the more gentle, the more torturous