Level 25 Teambuilder

So, I'm trying to get a few friends into the game. One of them finally got the courage to try a PvP game. I suggested we do Teambuilder so he could be guaranteed to get bot-lane marksman for a role. However, I couldn't invite him. And when I tried to get him to invite me, he told me it was unavailable until level 25.

Why did you guys change this? Teambuilder is literally just a better version of Blind, yet I can't have my level 10 friend play that game mode because... reasons? It used to be that Teambuilder was the FIRST thing players unlocked. And that was awesome! But now we're stuck trying to fight over roles with less than 10 seconds to finish putting our team together. And I'm sitting there (as the advanced player) trying to fill, but can't because we have 2 people who want mid-lane and 2 people who want bot-lane marksman.

Could I be given a reason why Teambuilder now requires a player to be level 25+? Or better yet, just return it to how it was. I hate not being able to play with my newcomer friends because Blind is such a garbage queue but we have no other options.