I've worked at several places that didn't have formatters when I started. they did by the time I left. you can incrementally adopt them and if it's automated most people at worst don't care. advocate for things you want

We use formatters, I just disagree with our current conventions (nitpicky, I know).

hate to break it to you but it behaves like a variable either way. function just behaves closer to a var variable. const fns are less like variables since no assignment. intellisense/devtools all show them just fine. it really is just a minor aesthetic difference on the definition

To me it's about readability and declaring everything as const goes against that.
What benefits does it have? Using this in arrow functions is still valid it's just that they will use parent scope to resolve it. You saying it doesn't have this or arguments doesn't convey any benefits (nor real drawbacks) to me. Hence the convention feels useless at best.