I never use split-screen view for Markdown. Split-screen makes sense for something more abstract like latex or html. But I do not see the benefit for Markdown. I would much rather have 50% of my screen.
I quit social media two years ago, and while I think I am generally happier and less anxious, I am also left out. When everyone else has seen someone's new baby pictures or a picture from the summit of a mountain. Sadly, I am growing apart from my friends faster.