Since in-game examples are top tier (and I just got my DC back) I will provide some of my own.
1. point blank Sagat lvl3 tiger raid.
WITHOUT JD, I am stuck in blockstun the entire time until it is finished.
WITH JD, After I JD the 3rd hit I come out of JDstun and can hit Sagat (DP/Super/whatever)
Shorter blockstun allows me to recover before I normally could without JD.
2. point blank Sagat d.MK
WITHOUT JD, I cannot hit him after I block it with reversal SuperFB, or ShinShoryuken
WITH JD, I can easily SuperFB or ShinShoryuken him after the d.MK
You might be thinking “oh, that might be because of the no-pushback thing”. It’s not. I can JD the tip of his d.MK, and still land a SuperFB. Much farther than normaly blocking a point blank d.MK. I can even d.MK into SuperFB after JDing the tip of his d.MK.
If I have any advantage at all after normal blocking his d.MK, it must be horribly small. However, If I JD, I must gain quite a substantial advantage because I can hit him so easily.
So JD gives me frame advantage in these situations, yes?