more like 99%. More. This is nonsensical. I have rigid (gravel), hard tail (fat bike that used to be rigid now has Mastodon fork) and full suspension bikes (XC and enduro), and 100% of the single track I ride (and its a lot and varied) requires a suspension fork and I'd estimate that 80% of it is ridden faster on full suspension vice hard tail. 20% would be be really sketch/dangerous on a hard tail. Could it be ridden on a rigid. Sure, it's possible, like its possible to ride a fat bike in a criterium.

And the axle to crown distance on a fat bike, eg, Trek Farley is 531mm w/out sag correction (511mm with).