“ standing for long periods of time might not be much better than sitting after all”

Well duh, if you trade one sedentary all-day posture for another sedentary all-day posture it’s not likely to be of much benefit.

The point of standing desks is to vary posture during the day and being able to choose to stand or sit while continuing to work gives you one more way to achieve this. Mix with breaks and walks and it’s starting to look better than sitting on your ass all day anyway.

I try to stand for calls/remote meetings, I have a couple every day and it adds up to about 1h of standing / shifting my weight around and helps me stay focused. But not overdoing it is key - on days where I have more than a couple of meetings I’ll totally be sitting for some of them.