I think it's worth noting that 10PM news has long been successful in major markets like New York City, Boston and so forth. But that's only because those ARE major markets with millions upon millions of potential viewers. With so many people in the viewing area, it's easy to find "enough" people who don't care for prime-time network offerings, and would prefer to watch the news instead... especially when you consider these major market 10pm shows all started decades ago, when there was no such thing as cable TV, and when these stations didn't even HAVE a Fox, CW or MyTV to be affiliated with.
Even if the ratings pale in comparison to "the big three" at 11pm, a so-so rating in NYC is still a lot of eyeballs, compared to a so-so rating in Rochester.
In major markets, most 10pm news operations are also fully-staffed, completely independent of another newsroom. WPIX does what it wants, when it wants, how it wants. Their reporters are focused only on the WPIX product. It's not like WPIX is going on at 10pm with reporters fronting only vo/sots to "preview" bigger packages coming up on WCBS at 11pm, for example. Even in Albany, Fox affiliate WXXA is independent. Their reporters aren't being asked to turn a vo/sot for 10 while working on a package for 11. They're focused only on WXXA and nobody else.
But in Rochester, Syracuse, and most other medium/small markets, the 10pm newscasts are produced by a bigger station, where management and everyone in the newsroom KNOWS 10pm has never been, and never will be, a bigger priority than the 11pm newscast. A reporter working on a story for both shows will always see the 10pm version as a burden that needs to be quick and dirty so they can get back to putting put their heart and soul into the 11pm version. Why? Because they know more people are watching at 11. Making a better effort for the 10pm newscast won't bring more people into the 10pm show, but putting the lesser material on at 11 will certainly damage you at 11.
Some "experts" say the national trend shows more and more people are watching morning news. If there's enough viewers up early enough to make it worthwhile for newscasts to start at 5AM, that means these people are already in bed by 9-ish -- and therefore not watching ANY late newscast at 10 or 11.