Do I think the targeting of swing states where she ended up losing by a few thousand votes mattered?
Sure. I think that's a reasonable assumption to make.
It's not a binary situation.
Russia successfully helped influence the election, Hillary's poor strategy had an effect, the leaking of the DNC's emails had an effect (also perpetrated by Russia, but also they were corrupt).
Regardless of the opinion that it had an influence, Trump has essentially rewarded Russia for doing so, unless he has the opportunity to blame Obama for it. James Comey's questionable judgement to make a story out of what amounted to be nothing a few days befor the election had an effect.
This all seems pretty basic to me.