I guess reverse proxy as a service exists, but I pay for a 2 core vps unit, its like $10/month to route all of my ingress traffic. The main reason is security, complexity, and just general ownership of my data. Running all of my services on an vps (with storage) would be prohibitively expensive. I pay for the hardware once. Use it for a while, then upgrade and sell off the old gear. I don't like renting ANYTHING if I can help it :)