> There is nothing at all in nectar that is known to be of the slightest importance to honey bee health other than sugars. 
> Are there any studies on this? I’m thinking Peter B. might have something.

Dick was talking about the value of nectar, not pollen. But nectar is not pure sugar, as evidenced by this old piece from Apidologie. 

Baker, Herbert G. "Non-sugar chemical constituents of nectar." Apidologie 8.4 (1977): 349-356.

This brief review describes and discusses some chemical substances that have been found  nectars. Amino acids are universally present.

Nectars are richer in amino acids if the flowers that produce them are pollinated by settling moths, butterflies and many wasps which, as adults, do not have alternative sources of protein-building materials. They are weaker in the cases of flowers pollinated by bees and bats (which utilize pollen as a nitrogen source) and birds that catch insects. 

In addition to potentiality for increasing life  span and reproductive output of pollinating insects, amino acids in nectars of all kinds may  help to provide a distinctive « taste » to the nectar of each species. Nectar amino acid complements appear to be strictly controlled genetically; these complements have a use in taxonomic and phylogenetic studies of congeneric species. 


Newer work has bolstered these observations:

Folly, Arran James. The impact of plant chemicals on bee health: Interactions with parasites and immunity. Diss. Royal Holloway, University of London, 2019.

Pollen and nectar contain phytochemicals (Baker & Baker 1975, Adler 2000, Stevenson et al. 2017) and these may be consumed by foraging bumblebees. ... some may have antimicrobial activity (Cowan 1999) and may therefore indirectly benefit bumblebees by controlling pathogens and parasites.

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