you can. but this can open up way more flexibility on how you run those services. think about something like docker where each app may be running web/db/queues

you can. but this can open up way more flexibility on how you run those services. think about something like docker where each app may be running web/db/queues/mail/etc. with v6 each docker app/service could have its own ip so you can run on the default ports. you could even create a subnet per app to segment them off easily.