Making the game available on Mac is a bit of a struggle for us, because none of us have a mac. This means the only way we can build the game afaik is on a build server and then we still wouldn't be able to test the game at all. Right now the effort is not worth the benefits, because, as you pointed out, you can still play the game in the browser on mac.
Maybe this will change in the future but for now it will stay the way it is, sorry :c