Why does my rank up game to Gold have 2 deranked diamond players boosting their 3rd?

Replay ID: 10551184516

Gambit - dia 3 and Groot - dia 2 both deranked to silver to trio party with elsa to boost her.

Its not the biggest deal to lose it but just a laugh at the thought of EOMM trying to give you the toughest game possible on rank up and then I get this.

https://preview.redd.it/pja2pq5ufplg1.png?width=1443&format=png&auto=webp&s=58b5c06f3ff23bab7b6aeee71e2ff18053fe7587

"Go play ranked if you don't want to play against diamonds"