It's also not like you'd have to have a separate server/vserver for every such project, a very affordable vserver will run quite a lot of nginx containers. Plus I guess some people will have a vserver or something like that anyway (I have a small one to get around NAT at the ISP level), in which case it might be net-zero.
My ISP puts everyone behind some sort of NAT, which means I can't reach my home network from elsewhere since I can't open ports. They'd let me buy my own IP address for a monthly fee, but I've found that an old Pi I already had, an autossh-ed reverse shell, SSH forwarding and a cheap cloud instance work just fine for checking sensors and the like, cost less and the cloud instance has other uses, too.