It is because each queue has its own "ranking" or mmr attached to it. So they probably never play TB and got matched up with you.
I guess you can say this, but this should probably have to go both ways, right? Technically ranked 5's, ranked solo q, normal solo q, and team builder are ALL played on the same map. I normal blind pick I usually run into diamonds/plats, but in solo q ranked I'm only gold. Is it fair for me to automatically get diamond rating for not actually putting any effort into it? Also, I feel the only reason you are upset is because you are going into the game with the wrong approach. You should be going into it to try and learn and get better, while having winning be an added bonus if you can pull it off. I feel the main reason for you being upset is you just wanted to win and saw it as things being stacked against you. If you REALLY want to win so much, you are better off playing against bots. If you actually do run into higher level players, use it as an experience to play against people you would most likely never be able to run into normally and try to learn as much as you can from it.