Yes, in games he isn't seeing action but you notice he has a headset on. He hears everything going on, on the offensive side from every offensive coach. Play calls, routes, blocking schemes, etc. etc. etc. He is learning how he needs to read defenses, where Taysom in making mistakes, where the WR are making mistakes, where the RBs are making mistakes, and where all of their successes are as well.
Tanner still gets to practice and implement what he is learning as well. The kid is going to be great next year because he is soaking up so much knowledge right now. No it isn't experience and I absolutely agree that in game experience is more valuable.
But lets not pretend Tanner is just sitting around with a clip board picking his nose. He'll see some action later this year and will show to be 2 steps ahead of Taysom come next year.