Why do celebrity actresses and models do that pose where they angle their leg diagonally/45°?

I used to do photography as a side gig, with an interest in fashion and portraiture. When I was dealing with new models or doing portraits for friends, I had to do a lot of posing with people who don't know how to position themselves for the camera.

Feminine bodies tend to look better on a 45 degree angle, making the entire frame look slimmer. Our stupid brains tend to only see the width in the image. Masculine bodies look more powerful facing the camera straight on, and with the lens higher than the subject, which makes an inverted triangle shape. Broad shoulders, skipped leg day, etc. For young guys, I'd generally get them to crouch, look up, and get up on a ladder, and then zoom in on their head & shoulders. Magic. Old guys can't crouch. Bad knees LOL

High camera can also work well for some women, but tends to emphasize chest size, which isn't always appropriate given what the portrait needs (ie, we doing a business headshot or a sexy dating profile?)

Its not a conspiracy man, I swear bro

takes a bong rip

Add the angles up on those subsquares, they ALWAYS add up to 180 degrees i.e. -> π. EXPLAIN THAT.

All triangles add up to a WHOLE PI even when they are slices of a pie themselves!?!!! Does nobody else see there is obviously something fishy going on?

Same reason if you photograph a bunch of weight lifters they are going to pose to hilight a thinner waist and bulky arm/chest or god leg development.

Its a single snapshot that can capture your best or worst look.

Women posing are going to accentuate a leg or heel, rather than standing straight on with two boring front views of identical feet. Trends happen too, remember the bent over butt out pose that was super popular in the early 2000s