Could the Russians have tipped a few close elections? Probably. Today's political parties know there are certain campaign tricks to convince the soft support not to vote. If the Russians (or big businesss) also uses these tricks, should we not focus on the system instead of the nefarious players?
When the "good guys" win a close election, we can dance in the streets. But the losing side is still a festering sore that can cause problems later.
Without the Russian (or big business), our system is still unbalanced.