The issue isnt if ROMM or LB separately are ok if used responsibly. The issue is LB owners would have to rely on the whims of a third party that is doing what they do to not get them into hot water by relation, as again, money would be involved. Its much easier (and hard enough) to manage stuff you have full control over.
Imagine if LB implemented direct archive.org downloading direct to bigbox. or implemented WiiU USB Helper integration. And many more, would be super awesome but it would catch upto them at some point. A big part of legal protection is obscurity and plausible deniability. You cannot make this sort of stuff TOO easy for the end user