Outside the now, well supported evidence of Russia's involvement in the hacking of the DNC emails we have massive donations to groups like the NRA, political campaigns and hiring people like Maria Butina to influence politicians. We've seen them try to meet with Trump's family in order to provide them with damaging information on Hillary clinton in exchange for dropping sanctions. We've also already had indictments of people within the Russian government that were apparently involved with the disinformation campaigns. With lots of information about their groups and US based organizations they used.

You have to ignore the information available to you to claim the extent of their interference wasn't broad.