Valve started to ban accounts for using bots and boosting services.

here is example of game

Many users who bought low priority boosting got bans for 8 years, because their games played against 9 bots.

you can read more stories and bans in reddit:

https://www.reddit.com/r/DotA2/comments/72rvak/low_priority_bot_abusers_receiving_8_year_bans/

i Hope we will have more skilled unboosted players in future in our mmr brackets, no more account buyers and boosters.