Slightly loose handlebar controls is a long standing dirt motorcycle thing from way back and not a bad idea at all. I should buy a lottery ticket because now that I think about it, I've yet to break an MTB lever. Trust me...that's not from a lack of trying or having getoffs. I've broken maybe a couple of dirt motorcycle levers over several decades, but the slightly loose clamp has probably saved me quite a few. Good advice.I’ve dropped my bike or had the occasional crash. All the things mounted on our bar are exposed to breakage which is why I now don’t over-tighten any clampy-things on my bar. With some reasonable force they spin on the bar.
It’s not 100% protection but it can help. Snapping a master brake cylinder can be expensive. I’ve done that.