Right, like if you just rephrase OP’s question as what’s the point of a sports bra, it becomes more obvious. Everyone knows what a sports bra is for, right? Well with significant enough breasts, virtually all movement benefits from some support.
The weird thing to me is how women with very small breasts can still sometimes adhere to a strict bra regime. Some of it is cultural programming, including the terror that your nipples might show through a shirt. This IMO is not worth the cost and maintenance and restriction of a bra.
When people poop on Muslims for covering their women or wonder how some women could ever want to wear a veil, I like to remind them that we do exactly the same thing in the West. It’s just that our bar is set at a different level. No we don’t lose our shit if women show their faces but we still lose our shit if their nipples show.