I would draw a line at user customized wall of content. All content on sites should be organized in a similar way for everybody (by date, by category, etc.). I think this would reduce a lot the problems that we see currently.

If you want to be bold and imaginative, although doubt this would ever pass, any platform that focuses or allows user content, should not be allowed to show advertisements. Then the incentive to have people stay more to watch more ads would disappear.