For centuries children and adults did ok treating broken ankle with home remedies. Why can't i?

You are Incorrect !! Some people will heal with compression, splinting and ice. But some people are permanantly impaired without proper casting or surgery if needed.You are misinformed if you believe everyone with broken ankles healed without any problems, before the onset of modern medicine. If you wish to gamble......?
You can. Just be prepared to live with a bad result. Good treatment depends on the specific nature, location and degree of displacement of the fracture. Some require surgical fixation while others need time and a splnt. Get an expert opinion quickly so all your options are available.
Are you sure. Are you sure people "did ok" with home remedies for ankle fractures? some ankle fractures that do not need much beyond short term immobilization. We usually use a cast or splint but back years ago they may have used a broom handle and a belt. But there are other fractures that we know will leave a person crippled unless they have surgery and so we do believe we offer a better outcome for those.
Go ahead. If you are seduced by the idea of DIY health care like they did centuries ago go ahead.What you do for yourself is your own choice.If you are happy to place yourself in the same era where the anticipated lifespan was 30-40 yrs, go ahead. With a broken ankle, be ready to deal with the sad outcome of non-union, where the broken edges never seem to knit.You can surely fashion crutch with simple tools.