It's at best an indicator that the woman isn't about to die and could maybe push out a child. Nothing more. That's really not super helpful and I doubt that it's anything remotely close to what most people are thinking about when they swipe and try to get a date with somebody.
I think people date and romance because largely it feels good, and it instinctively feels good because it satisfies certain necessities of life. Some of which necessitate pairing with the opposite sex. I don't expect the masses to be able to explain their instincts,or for their thoughts to explain them.
> That's really not super helpful
But it's more helpful than most of the other social media fast alternatives of someone you don't know well. You won't be getting their medical records. On a thirty second first glance yay/nay a few healthy photos looking good doing aerobic activities is as close as you're going to get to evidence of sexual fitness for fetal survival without asking intrusive and creepy sounding medical questions.