Typically when someone tells me that a hummingbird doesn't go to any of their feeders, it tells me that it's a young bird that doesn't understand them yet. Hummingbirds get virtually the same thing from from feeders as they do from flowers, primarily sucrose. Even though the concentration of sugar varies from flower to flower, they will feed enough to fill their required calorie intake. The difference is with feeders they can gain these calories without expending as much energy. It's kind of like placing out a bird seed for other birds in one condensed feeder. They don't have to search all over to find the seeds, therefore using up less energy. Compare seed eating birds to hummingbirds in the way that they both want to gain the most amount of food value without having to work as hard to get it.
The reason I want a large variety of good hummingbird flowers in my yard is to attract young hummingbirds that are naturally attracted to them. The more flowers you have in your garden the longer time young hummingbirds will stick around until they solve the feeder mystery. Of course, if you have loads of adults feeding from feeders in your yard, the young will figure them out pretty quick. This nectar is a necessity for the quick metabolism of hummingbirds, in order to keep them moving and feeding on the needed protein they will find in small insects. Understand that these birds are opportunistic and will always revert to the method that provides them the most food with the least effort. But until they solve the feeders, flowers are a necessity. 2014, N.E. of Edmonton, Alberta.