the problem with old.reddit.com is that it actually is a terrible UI. If you make a site that pixel-perfect mirrors old.reddit.com, the only users you'll attract are the vocal fans of that UI. i've been a reddit user since digg died, and i remember when we could all agree that reddit's UI was the worst. the fact that the newer redesigns are somehow even worse than the old UI doesn't make the old UI good.

a social site populated entirely by contrarians who think old.reddit.com is peak web design is not a site that anybody will want to visit.