The clean way to build this is with firewall configuration, opening ports, and static IPs. NAT/STUN and dynamic IPs are just a hack and I don't understand why people pretend this is an acceptable solution for professional networking. Working around an infrastructure that isn't a natural law but can be changed at our will seems like a big waste of time.
Because it IS acceptable for many cases.
Many businesses don't operate in such a way as to have centralised infrastructure solely for providing internal networking, nor would they want to add the additional administrative or unnecessary routing overhead.
Even locations that would traditionally be considered highly centralised often have some form of dynamic network fabric as an overlay. Pretty much the entirety of cloud infrastructure runs on such systems, and they seem to do OK.
A change in an IP lease should result in no downtime whatsoever, because addressing is not the same as routing. A routing change would have exactly the same effect on a static IP.
I then pointed out that an overlay network means you don't have to worry about that anyway.
I think you need to reread whatever comments you think you are responding to, as there is clearly something out of sync with your replies.
As for your bandwidth concerns in the case of needing to relay, you can even set up your own relay (https://tailscale.com/kb/1118/custom-derp-servers), which would satisfy your desire to be more centralised (i guess you could force all traffic through it, but cant think why you would want to) while still allowing the flexibility of the overlay that tailscale provides.