How do I remove classless divs around my paragraphs?
In the theme stable the field twig has two div's, one overall and one for each item. This would match what you have provided as html markup.

So this should work, copy field.html.twig from stable to field--entity-reference-revisions.html.twig in your theme and remove the div's from there.

That the div's are useless is not correct for all circumstances, because there may be different configurations or modules, which use the attributes of the div's. So if you remove them, you might loose some of that functionality.