With all our popular narratives about the inevitability of scientific progress, it's always refreshing (from a historical point of view) and important (from a personal, ethical perspective) to remember that there's no guarantee that chronologically later developments will necessarily be improvements on earlier conclusions.
It brings to mind our current replication crises in science.
And even if in this case the initial solution was correct, it was still observing a correlation, as they had no clue why lemons do the job.
My conclusion based on the article is that just experimenting is not enough, you also need to develop and test a complex understanding of the system. We probably don't cherish enough as a society, that some of us (as in: trained researchers, etc.) have a mindset that expects both replication and understanding, even if being humans we don't always reach this ideal.
Basically, it's easy to think we understand something when we have a solution to it, but the two should not be automatically conflated.