Oh really? How so?
Shakehand primarily focuses on both forehand and backhand, making it reliable, albeit not too powerful on both ends.
Cpen's fingers are curled, leading to weaker offense but the ability to create the iconic RPB.
Jpen's fingers are straight, maximizing attack on the forehand side but crippling the backhand side.
That is what I think for the 3 main grips, so I personally believe Jpen is the best attacker. Ofc, it depends on the player itself, but based on grip alone and no skill differences, Jpen is most likely the most powerful attacker of the 3.
there is no more jpen players any where on the elite stage in any country.
even cpen (which is stronger than jpen, hence that is why it lasted more than 1 to 2 decades longer) is slowly fading out.
Felix Lebrun is a rare case.
if Jpen is really so "special" as you put it, then you would see a lot more of them. but it is 1 to 2 decades gone already.
Jpen was good for speed, and that is 38mm days + speed glue
when 38 shifted to 40mm, it loss its speed
and it only have serves left and that too was lost when hidden serves was banned.
With modern table tennis today, jpen has no more advantages, so even jpen heroes turned coaches are avoiding jpen and teaching players to play shakehand rather.
hope that sums it up.
PS. I guess you haven't seen Ma Lin's forehand in person. he would out FH rally your jpen olympic champion or even the next 5 best jpen players any day. Felix would probably do too, even Xu Xin.