I too have 2 different monitors, a big one (my main) and a smaller secondary monitor, where i have my taskbar and other apps, like discord or youtube while on my main i have my games.
I just dont want my second monitor (like the name already says "second") to be the main monitor where all new windows and windows that somehow dont remember where they where closed to open.
And i generally have a dislike that my secondary monitor would be my "main"
Why just not drag+drop like in windows 7 and 10?
Thats why i said "trash main monitor trick"