Good point,The thing with this client is they wanted to mitigate the risk of removing a large number of links so high quality link building was moved in early before keyword research. So it is on a case by case basis, but defiantly a good point for most new clients I work with who do not have pre-existing issues you want to do Keyword Research very early in the process.
If both page are closely related (lots of topical overlap), I would merge the unique content from the lower ranking article into the top ranking one, then 301 redirect the lower performing article into the top ranking one. This will make the canonical version more relevant, and give it an immediate authority boost. I would also fetch it right away, do some link building, and possibly a little paid promotion to seed some engagement. Update the time stamp.
Although it may have changed slightly since BrightEdge published its report last year, the data still seem to hold true. Organic is simply better for delivering relevant traffic. The only channel that performs better in some capacities is paid search ads, but that is only for conversions, not overall traffic delivery (Paid Search only accounted for 10 percent of overall total traffic).