Open primaries has always been the norm? In what reality? We don’t even have open primaries in my home state. Heck, primaries only became a thing in this country in the 1910s.
Not to mention the fact that unless you live in Iowa or New Hampshire your choices for candidates are narrowed down significantly due to most of them having dropped out after the earliest of primaries. And at the end of that day half of the primary elections mean nothing by design, as the presidency is a winner take all system.
Now for this specific election cycle, be honest, who else was the nominee going to be? There was uproar from both sides, especially on this stream in particular for Biden to drop out, and when he did, the Right had a hissy fit that their wish was granted while the Left united behind Harris. And that’s the key. The Left WANTS to vote for their candidate, regardless of how she got the nomination. And if the majority of the Left’s voter base’s wish for presidential candidate is fulfilled, then who cares how they got there? If the party chooses an unpopular candidate, the voters make that known by not voting for them. And if the voters want more say in that process, they also make that known. But given national primary turnout isn’t even at 50% in any state for both parties, data shows that at the end of the day, we’re all voting for candidates selected by a vocal minority