All true, but imagine you didn't have these browsers sitting between your code and the native OS. Would that be any cleaner? At least browser vendors do try to

All true, but imagine you didn't have these browsers sitting between your code and the native OS. Would that be any cleaner? At least browser vendors do try to conform to some common specs and any deviation from the spec can be bridged using JavaScript libraries. Without browsers as a target you might find yourself supporting ancient Android versions and Windows XP.