I know teams in normal games can be pretty unbalanced sometimes, but that seems a bit too much

So we queded up as a group of 4 plat players, just to face an other group with only unranked/bronze/low level player. Whilste we got another plat guy as a random, they got another low level player. We stomped them within 17 minutes, we could have been even faster if we had tunnel visioned more on winning then killing them. How was that even fair for them?