French here. It is all about the IT sovereignty (souveraineté numérique). The idea is to use French solutions in order to limit leaks if confidential information and dealing with other country without worrying about threat of limiting, stopping critical services. Also it is easier to apply EU laws like GPDR.
That is why all the French private company dealing with sensitive information (military, cyber security..) are only using French solutions.
I get it, but I just don't get why wouldn't they just follow other govs' steps and just set up a matrix server instead. It's already available and proven.
Yeah I mean you’re not exactly shedding some deep insight here, it’s very obviously that. While there’s merit to banning WhatsApp, it’s just foolish to ban signal. It’s the best in class for a reason, and it’s open source. France should devote resources to auditing and supporting signal if they really want to throw money to developing secure software.