I think people not being able to vote because their right to vote has been taken from them, or their vote was made pointless through gerrymandering, or because of other acts of voter suppression does change elections. The ability for it to change the outcome of a race is why voter suppression happens.

People who don't bother to vote for any reason changes elections. It also makes it very hard to make claims about what the majority of Americans want, since so many didn't make their opinions known

In my experience in Texas, the right-wingers have this system set up where votes that were legally cast can be denied validity by some sort of "citizens election integrity board." I had no issue voting in Travis County but when I moved to a more conservative suburban county address I ran into this. There's a multitude of ways for anti-democratic forces in the US to deny citizens their rights. And it really hardened my opinion of these sorts of people that would do that to me and others. If they say my rights aren't valid how valid are their own, certainly nothing I should respect given their treatment of myself and others. That's why I have no tolerance for the right-wing I've seen their real face.