Why?????

Because they can pick wjayever champions they want? The game cant .match you with someone at the same mastery level since, you know, you match before champion select?

Quit being ridiculous, it's not their fault they like playing those champs and no one on your team picked mains.

They are likely premade with the low levels on their team. The other team also has 2 high level accounts that look like they didnt want to play their mains.

Welcome to normals.

You're sub-30. There are very few sub-30 players and tons of them group with friends who have been playing the game for a while. This is EXTREMELY DIFFICULT for matchmaking so you just kinda have to suffer with it until you hit a sort of minimum threshold of experience where there are enough people playing.

Also, level is not a good indicator of skill past 30 except in huge disparities. It's quite possible your 140 is an equal or better player than their 240 and this comes down to be a fairly even match.