You're absolutely right! I kid. I'm also a former avid user of the em-dash, but have mostly stopped using it. I've even started replacing em-dash usage with commas, which often results in a slightly awkward, perhaps incorrect, but quaintly artisanal sentence with a LaCroix-like spritz of authenticity.
My double-space-after-a-period though, I will keep that until the end. Even if it often doesn't even render in HTML output, I feel a nostalgic connection to my 1993 high school typing teacher's insistence that a sentence must be allowed to breathe.