The FR64S, 66S, and 64fx all do have an anti-skate device built in. So maybe Ikeda was pinching pennies when he designed the lesser models you mention.
I kind of disagree that the tonearm and the cartridge make a “big” difference with respect to the skating force. The skating force is generated by the friction of the stylus in the groove. So I would say the stylus tip shape may make a difference to the amount of skating force. However, if the bearIng is very low in friction, and if the headshell offset angle is designed for any one of the three popular alignment algorithms, then the tonearm really shouldn’t make that much difference. The reason it could make a difference is if the friction at the bearing is on the high side. Thus some of the VPI tonearms that lack an anti-skate device generate an anti-skating force by virtue of the drag caused by the tonearm wires where they exit near the pivot point of the tonearm. I suppose that is true for some other tonearms that just happened to have a lot of bearing friction. I guess I agree then that if you have one of those tonearms which has friction at the pivot due either to bearings or wire drag, either of those factors could lessen the need for a separate anti-skate device. I suppose also VTF can make a difference.
Maybe we’ll find out that the OP is using one of those VPI tonearms, and then we won’t wonder why he does not seem to need a separate anti-skate device. Or maybe we’ll never find out what tonearm and cartridge he uses.