Yeah, I do see too many people on the left worshiping McCain simply because of his vote on the ACA gutting as well as Trump's shitty comments about him not being a war hero, which gave people the kneejerk reaction to defend him.
The left mostly turned against him with the 2008 election and singly because of Palin. He gave Palin a national voice, which is an act worthy of universal condemnation. Prior to that, almost anyone saw him as a superior candidate and a superior human to George W Bush, very likely would have won against Gore, and would have likely been a superior president, and probably quite popular. It helps, of course, that Karl Rove and Dub trashed the man and his family in several completely unforgivable ways. The robocalls in South Carolina are a thing of shameful campaigning legend. He deserved much, much better, and of course he wins much sympathy for that.
I don't think anyone doubted his honest love for the country, but certainly many on the left disagreed with him politically and, it can fairly be said, how do you constantly defend the honorable things a guy says when he votes in the opposite direction?
Yes, voting down Trump was certainly a big deal. It was big for this country, and it
was necessary. It's important to note that when the FBI brought the actionable intelligence regarding Trump as an agent and target of blackmail for Russia (during the general campaign), they went to McCain: the only person in the party that clearly hadn't lost his marbles over Trumptardia. ...telling, considering that he also had tumors ravaging his brain at the time.