I'm not suggesting overlay networks are useless (Slack uses it to connect thousands of machines around the world!). My comment is aimed at the self-hosting community using them as a VPN replacement for remote management / access. I don't see how they are any better than VPNs for this. They're probably worse once you start connecting all the devices you aim to remotely manage into a flat network (mixing internet facing devices that should be DMZ'd with internal devices).