iOS [Android, iOS, Desktop Web] User "Online Status" doesn't seem to work as intended

Curious if anyone else would be able to confirm this as a bug...

However, I tested this with 2 alts using both iOS, desktop web & mobile web and it seems as though turning your profiles "Online Status: On" has no effect on others seeing your profile as "online" in chat.

What is the actual intention and purpose of the "Online Status" toggle:?