I stand corrected. Everyone listen to 👆that poster.
My state (Louisiana) has a different election system — actually several and it’s currently a confusing mess — and I’m not really familiar with Vermont’s primaries.
In Louisiana, the November election is actually technically a primary. If no one gets 50%, the top two candidates (regardless of party) have a run-off in December. For various reasons over the years, some elections were changed to be more like first past the post with closed party primaries. Others weren’t. And now, it’s just a messy hodgepodge. (And to top it all off, our governor and many other elections are “off-year” so it doesn’t align with federal elections. We’re voting on Amendments on March 29th. It’s idiotic.)
That’s probably the Occam's razor explanation. I obviously have no proof for my little pet theory.