It's interesting that none of these papers seem to be coming out of academic labs....
Checking if a recommendation system is actually good in practice is kind of tough to do without owning a whole internet media platform as well. At best, you'll get the table scraps from these corporations (in the form of toy datasets/models made available), and you still will struggle to make your dev loop productive enough without throwing similar amounts of compute that the ~FAANGs do so as to validate whether that…
Most of these papers are specialized increments on high baselines for a primarily commercial problem. Likewise, they focus on optimizing phenomena that occur in their product, which may not occur in others. Eg, Netflix sliding window is neato to see the result of, but I rather students user their freedom to explore bigger ideas like mamba, and leave sliding windows to a masters student who is experimenting with intentionally narrowly scoped tweaks.