Riot not supporting team builder enough?

so i was going over the available game modes for PVP Classic summoners rift when it occurred to me. Why the heck is the Team Builder unlocked at 25? it seems like that would be the best game mode to start with when you first join the darned game since it would obviously assist in new players getting a better understanding of how the game works in general. You can argue that they might not know what roles go were...though i could have sworn it lists what lanes are needed and what type of character's are supposed to be in each lane. The only thought i can come up with is secretly Riot doesn't actually care about promoting team playing from the people who are playing their game or the team builder set-up would be a level 1 available thing, either that or they haven't thought of such an idea as of yet, and if that's the case then just take this idea and implement it. any thoughts and opinions from people? adding a vote option, don't know if it will make a difference but if enough people support this idea maybe it will, for sure it wont make a difference if i don't post anything so it cant hurt.