- 2 bad dps players is better than 3,4 or 5
- role based SR improves match quality
- guarenteed 2 supports enables tanks/dps more and stops games with 3,4 support mains happening
Etc
Plenty more reasons why it will improve stability and increase chance of actual competitive games here.
With a role que you would que for your role. If u que for support and throw then u are not only extremely weird but u will have an awful support rank and hopefully get banned. Im more than happy to see selfish dps players get banned for refusing to adapt personally.