Does "A is true of B." a general expression? Or is it an extraordinary expression that is not used in daily conversation?
"Something (is true/not true) of something" is a somewhat common expression, although usually it is "for something" instead of "of something". This expression is more likely to be used in a scenario like reporting news or doing some sort of broadcast rather than conversation, but it is not wrong to use it in conversation. Ex: While many children like candy, the same is true for adults. That's why there is candy marketed for adults.