Having two sidewalls available such that u brackets work is probably not a good use case for this hanger. Usually it means you're inside a closet?
But I agree you could build/attach small sidewalls or simply blocks and use this u bracket. But we've entered DIY space since it's not a common package and "readily available" as a solved problem.
From comments I read elsewhere, there are apparently apartments in places like New York that have non-standard depth closets that don't fit regular hangers that these could be useful for, and the van-life crowd has also been mentioned. In both instances, a regular rod mounted on either side would work fine.
I think also the negative comments here are missing how commonly closets are built incorrectly without the correct depth for a coat hanger. Not every day, but there are enough people living in condos which had lazy architects/contractors and might appreciate the solution. I've lived in one and seen several others. I couldn't think of another solution besides kids hangers, which wasn't a satisfying compromise.
But I agree you could build/attach small sidewalls or simply blocks and use this u bracket. But we've entered DIY space since it's not a common package and "readily available" as a solved problem.