For the record, I gig semi-weekly, and have two students. I've been formally trained since 5th grade. I've toured nation wide with nationally ranked DCI caliber drum corps. I've played in jazz and big bands for the majority of my life. I also read standard notation, and know that the OPs question was simply, "How can I determine the rhythm of the songs on Chordie?"
And the undeniable answer is that you can't. Tabs don't provide for it, nor does chords charts. Standard notation provides a way to document every inflection, ghost note, mute, accent, and any other thing the artist may want to provide.
If it sounds flat, that's as a result of the performer, not the notation. Standard notation is used by every school. You don't finish Julliard or Berkley or Cornish without it.
So, do we need it to play the guitar, particularly given the really simple structure of most of the songs here? No. Is it the best way to demonstrate rhythmic intent? Yes.