Yeah, I think the author may be mixing up recommendations for dedup vs non-dedup. The solution is always to not enable dedup, it's a niche feature that's not worthwhile outside of very specific scenarios.
It isn't required (in the strict sense) to keep the dedup table in memory, the problem is that performance is dire when it doesn't. It would be pretty similar to virtual memory thrashing, when the table is not fully in memory.
