I get your point.
All you mention were certainly “holocausts,” but over the years “the Holocaust” has, for better or worse, come to refer to what the Nazis perpetrated before and during WW2.
BTW, for my historiography class in college, I wrote my main paper on the Armenian genocide. It was three months of intense research of primary and secondary sources. When I finally came up for air and composed the paper it took a long while before I could really digest it all. It was brutal.
And yet, to this day, the Turks deny it happened.
The Japanese deny the Rape Of Nanking to this very day.
I’m not trying to denigrate any groups victimized by genocide. Let’s recognize them all.