Good point. That is indeed a distinct fifth reason.

Here's a sixth one: for some users it can improve latency, bandwidth and/or even cost.

latency/bandwidth: because of weird peering agreements between ISPs / ASes.

cost: there are networks where consumers pay per MB for international traffic, but not local traffic. Consumers can sometimes establish a VPN tunnel to the local data center and get an unmetered international connection, because the data center has a different agreement with the monopolistic consumer ISP.