Lol hi Danaël, as someone in the official légendaires discord, your pfp was funny to see
Not sure about the actual reason, but French is generally an outlier in the world of dialogue syntaxe, as most languages I'm aware of use some form of guillements exclusively, be it "this", 'this', ﹂this (Japanese)﹁, «this» or „this“. I've rarely seen the dash system or anything that doesn't encase the dialogue outside of French.