Facebook and Instagram, sure. But plenty of people are more or less forced to keep WhatsApp either because of people they want to be able to message that refuse to use anything else, or perhaps even because they need to be in some WhatsApp groups e. g. for work.
Communication platforms aren’t like web browsers or operating systems where you can switch at will to whatever else works for you, you’re more or less reliant on everyone you know also making the switch.
I’m not aware of another one. Some other distros like Ubuntu and OpenSUSE ship AppArmor instead, which does similar things but isn’t considered quite as secure.
I know plenty of other popular distros don’t ship any Mandatory Access Control system at all which seems like a very bad security practice to me. Same thing with Firewalls.