The reason for this is that I wanted this to be a distributed solution. You can shard up the different routes across as many computers as you like and the front end will route and patchwork it together at the front end.

Along with that you can run the client over any number of computers and they will act as backups for eachother. So, if you turn off one computer, one of the others will pick up the slack.

I'm not super familar with ngrok, but if it does all that then I guess, beyond the technology, there isn't a massive amount of difference :)