I seriously wonder how you got to this conclusion about 8+8 Alder Lake being faster than a 16 core Ryzen 5950X.
If we talk only about 8 threads or less, then It should be faster, but after that the difference will become increasingly smaller until Zen3 turns out faster. Let's be honest, those small cores will have a lot less IPC and clockspeed than the big ones. At best It could be faster than Ryzen 5900X in multi thread but slower than Ryzen 5950X.
edit:
I will do a napkin math where in the first case Alder has 10% better performance than Rocket Lake in Cinebench and the small core provides 50% of big cores performance. In the second case It's 20% and the small core provides 60%.
Cinebenech R23 Single(
TPU):
Ryzen 9 5900X: 1622 (100%)
Ryzen 9 5950X: 1658 (102%)
Core i9-11900K: 1676 (103%)
Alder Lake 8+8: 1844 (114%)
Alder Lake 8+8: 2011 (124%)
Cinebenech R23 Multi(
TPU):
Core i9-11900K: 13531 (100%)
Ryzen 9 5900X: 21707 (160%)
Alder Lake 8+8: 22326 (165%)
Ryzen 9 5950X: 25916 (192%)
Alder Lake 8+8: 25980 (192%)
As shown Alder Lake needs to be the second case If It wants to be a tiny bit faster than Ryzen 9 5950X in multi thread and this was just a napkin math, yet I can already conclude that It won't be significantly faster than Zen3 in multi, that's just impossible for 8+8 configuration from the info we got so far.
On the other hand, in mobile segment Alder Lake could be the fastest CPU you can get simply because AMD won't release anything higher than 8 core as a monolith chip and chiplet design is not very suitable for the mobile segment.