Unfortunately, some of the regular paint tools like eraser don't erase in a smooth antialiased way and just end up looking jagged (also only a square shape for eraser...no eraser brush mode unfortunately), so it ends up being a better looking option (well, when it works properly, which it does often enough to be useful). For whatever reason a bunch of tools and transforms (scaling, rotating), just produce such garbage jagged looking results, it's not serviceable even for those basics.