In 2016 the senate and the White House were held by different parties. Since SCOTUS nominations come from the executive, and are seated with advice and consent of the Senate, what McConnell did is not only normal it’s perfectly in line with a century of precedent. The idea that it was out of line, or against some nonexistent norm, is a narrative invented to make people feel better and discredit the court in the eyes of the public.
Prior to this Senate session, SC nominees could be filibustered. And every nomination prior to Brett Kavanaugh had bipartisan votes. The Senate is as responsible as the President for keeping the SC staffed with competent jurists. The role is meant to be apolitical. The first salvo was the nomination of Robert Bork by Reagan. He was a terrible choice but was replaced by Kennedy who was confirmed 97-0. Even Clarence Thomas got 11 Dems to vote for him. Mcconnell refused to even hold hearings for Garland or take a committee vote. That's an abdication of his duty.
Since the Senate was held by a different party, senators could have voted against Obama's candidate, couldn't they? But they didn't; rather, Garland wasn't ever brought to the Senate for a confirmation vote.
Because McConnell didn't care a bit about the people expressing the next Justice, he was more simply scared as fuck of losing that vote despite theoretically having a majority.
Since this is HN I will paraphrase Bryan Cantrill: "Do not fall into the trap of trying to anthropomorphize McConnell. You need to think of him the way you think of a lawnmower".
McConnell was given the power to do that by the rest of the Senators who put him in that position.
The narrative that Garland would have been confirmed if only he’d gotten a vote assumes that McConnell didn’t have the support of his caucus in what he did. That’s an incorrect assumption. They could have removed him and done what they wanted to do if there was some groundswell of support for Garland in the Republican Party. There wasn’t, they supported McConnell, and Garland wasn’t brought to a vote. That’s just how politics works.