[Polizeiposaune]

My understanding is that one factor pushing hyperscalers towards dual-socket was the cost of the network fabric - for the longest time, having two CPU sockets per NIC / per leaf switch port was the overall system price/performance sweet spot for many workloads. More sockets required more expensive CPUs, while single-socket servers need twice as many NICs and twice as many top-of-rack switchports.

With newer/faster ethernet standards you still need twice as many NICs but you can often split the lanes coming out of a switch chip and use a Y cable.