GP: > They exist because they’re popular and because the currently successful ones acquired or strangled all of their smaller meaningful competitors using investment capital and money from first mover advantages. Facebook literally copied Snapchat features into Instagram rightaway - Systrom even openly admitted it. That fits the bill of "strangled". Snapchat is in stagnation now, because everything it has is there on Insta.

Instagram and WhatsApp thrived only because Facebook acquired them, else both companies new they would be smothered to death. That pretty much fits the bill of "acquired... Using investment capital and money from first mover advantages".

They don't need you to use your FB account because they cross share data anyways. It's not like it's a painstaking operation to link different accounts, once you have all sorts of device data (which Facebook had, even on Apple devices up until recently).