These people I'm referring to, who want to occupy and hold ALL the listings on an item that show on the MB list, don't care about crashing their own sales, for the most part; their big turn-on is shutting out everyone else, like a kid hogging all the toys on the playground. And no, that's *not* the same thing as multiple people selling the same thing as you and/or undercutting. *Multiple people* is not same as "one person nabs ALL the listings that can show in the MB listing."
And why you apparently think "restriction inherently = bad," apparently you've never encountered reasonable restrictions in life. *shrug* But whatever.