I think this a good idea, but especially because the WayBackMachine uses good content security policies to prevent some of the intrusive JS ad-dependent sites l

I think this a good idea, but especially because the WayBackMachine uses good content security policies to prevent some of the intrusive JS ad-dependent sites like to push on people. So you're not only protecting from future 404 scenarios, but also protecting your visitors' privacy from unscrupulous ad-tech which seems to be everywhere now. The example provided in the article, showing how a site looked cleaner before, could simply be the content security policies at the WayBackMachine preventing the clutter from getting loaded, rather than any specific changes on the site - although I haven't checked that particular site.