I think the issue here is two-fold .... firstly, the player needs to prove that they're ready. Being ready implies that they've demonstrated that they can be reliable when called upon ... and it also tends to indicate a certain level of maturity in how they approach things. Secondly, the coaches need to be able to find opportunities to put them in situations where they can be successful (or where it won't endanger the outcome of the game).
Thus, for some guys, they demonstrate that they're ready right away ... then they can dip their toes in right away and play against some of our lesser OOC foes. The advantage of allowing some guys to play early is that if they demonstrate enough productivity ... then that allows you to make the determination on whether they even need to take a redshirt year. (some guys may simply be "too good" ... and the redshirt gets burned ... ideally for those guys, you want them to see the field early and often)
For other guys, maybe they need to physically develop a little more ... or maybe they need to grow a little bit more comfortable with their surroundings and the schemes, etc. Ultimately, players shouldn't just be given some playing time ... they ought to earn it. It's possible that some guys might earn that opportunity later in the season ... in which case ... they can still help the team later in the season.
Thus, to me, it's one of those issues where it all depends on the player and what they demonstrate.