Actually, just came across this tidbit in a cyclist.co.uk article, which to me offers the most sensical take on the matter:
"By his own admission, Simon Baynes of sportswear manufacturer Craft is ‘sitting on the fence on this one’. In his opinion it’s entirely dependent on the jersey material.

‘We make a jersey based on the properties of our Cool Mesh Superlight base layer, designed in conjunction with Fabian Cancellara and others, so when the jersey is constructed in this way it’s not necessary to wear an additional wicking layer.’"

IOW, if you're wearing an ultralight summer mesh type jersey, that's already built for ultimate wicking, there is maybe no sense in a base. OTOH, if you're wearing a regular medium or lightweight SS jersey, then a purpose-built wicking base does make sense.