In fairness, 4 socket servers are pretty serious money. Just the difference in cost for 4 socket capable Xeons alone puts them out of reach for many use cases.

  E5-2658 v2 (dual cpu): $1440 per part
  E5-4650 v2 (quad cpu): $3616 per part

As a result, I stick to 2 socket servers for Linux machines. I think the scaling out paradigm just works out a lot better, particularly for Internet services.