This is very far from the truth. Please note, definitions of throwing and trolling can vary and what you define as throwing may not be in violation of the Blizzard Code-of-Conduct. For example players could play off-meta heroes or be really bad in that match (we all have bad games after all), but that is not attempting to deliberately sabotage the match.
Remember to use the “Avoid as Teammate” feature to avoid your most recent players that you did not get along with. You can only save 2 players at any given time so manage it accordingly after each match. Furthermore, I generally recommend always taking a break after a bad match. It really does help more ways than one.
Finally please take a look at the most recent Developer Post that came out today about new changes they have planned for improving the community experience for us all. I wish you luck in your future games.