It's funny, I drill the back widow at my gym (non 10th planet) and my coach loved it. He loved the part where you flip the guy over into spider web. Months later, we're working a rolling sambo arm bar from back control... the setup is almost identical but instead of the roll you finish with a belly down arm bar.
Contextually, I think it's done because the Kurtka provides enough friction to finish from the top and Sambo rules require a faster finish.
My point is though, it's cool to see how closely related but different various grappling styles are. Those insights alone are worth the time spent on the mats.