There's more options coming in 036/040 for opening ports on your StartOS server, but that only helps if you want to expose it to your router, set up port forwards and directly expose your WAN IP address. 
Using a tunnel (like cloudflared) hides your WAN IP. That is not something StartOS can provide (unless they are going to provide some cloud services for it, but I didn't hear anything about that yet). 

 And using cloudflare you get all their goodies (basic ddos/bot protection, ssl certificate, url routing rules, etc.)