Binary packages not rebuilding against updated libraries

[Jan Stary]

On Apr 24 09:31:04, ken.cunningham.webuse at gmail.com wrote:
> Portfile authors need to manually "revbump"
> the library's dependent ports when
> supporting libraries change significantly.
> It's not automatically figured out by MacPorts.

Wait, what? I'm still relatively new to MP
and this seems a bit weird.

"Port A depends on library B. The port of library B has
just been rebuilt/upgraded. So port A needs to be rebuilt
as well now, if only to record the new dependency."

MP does not have that?