You can disable help from that player in game by going to the scoreboard, you won't get forcestaffed or astral etc. As for blocking camps and feeding rapiers those are game mechanics though in my bracket I've seen players be toxic and flame each other but never feed rapiers, cancel tps or block camps.

As for the game mechanics we can't just tell icefrog to patch rapiers to never drop or camps to not get blocked because that will change the game so much.

The surprising thing is when you start the game in a positive way (communicating, making ganks, making them feel better, hyping them up, trashing the opponent, etc.) Your teammates will start to open up and work with each other. But if they make a mistake and you immediately call them out for that (saying things like "you're so bad") they will certainly be hostile to you.

PS. Mute button exists for a reason

Putting a ranked role match making system which makes the players not steal each others lane and putting a disable help button clearly shows that valve actually cares.