From my experience you dont get past 6k by being a toxic dick. Most players become most respectful as mmr increases. That is because toxicity only tilts you and makes you lose more. The higher mmr games ive played in usually had nothing more than friendly banter (if players don't fight for roles.) and usually end with gg wps all around.

He wants to play with his friend, what makes you think he is doing this to pubstomp? I guarantee he will not talk shit afterwards (I have played with romantic girl I think its fear)

Also played with moo, QO, sumail and they usually just do their shit while their teammates 5k-6k do their shit. With the occasional direction 'rosh' or 'smoke gank'.

Even arteezy doesn't flame ingame he will flame you on twitch and assume you can't hear him.

All that being said even as a mid-high 5k player Ive gone toe to toe with the best of them, and unless they pick ember, storm TA meepo or one or those 1v5 heroes a 4-5k stack will have a fighting chance, no need to bitch about it.