Haha, No!
There are so many Kontakt libraries that such a general statement is
quite wrong!
The thing is: You have to look and listen to every library before you
buy it. Some are sampled with huge effects - some are very dry.
Yes, this aspect can be true: After several years of experience with many big libraries
I sometimes prefer tiny small old sf2 or sfz sample-sets, because simply they sound better,
they have that "character". I don't know why, and it might be mysterious ... but
it is true (at least for me).