While real musicians work hard at rhythmic precision, in reality this is never actually achieved and we probably wouldn't like the result if it was. If you take a recording of a real musician and import it into a DAW and then try to match each beat with the metronome function you will see that imprecision very clearly. There are subtle shifts in the rhythm and attacks on practically every note. Some of these are very small and probably random but others are probably intentional, either on the conscious or sub-conscious level, to make the music live and breath.
The usual example used to demonstrate this is Marty Robbins recording of "The Streets of Laredo" but if you do the same exercise with Arthur Rubenstein's exquisite recording of Mozart K511 (one of my personal favorites) you will see the same thing.
In other words, click tracks SUCK!
Specifically they suck the life out of music, IMO.
The random offsets of attacks and pitch by libraries are attempts to emulate what musicians do naturally. They work OK for mitigating the organ effect but they don't replace real musicians performing.