Earlier quoted context omitted.
What they mean is that the downloaded binary will have been compiled for only the architecture you're running on. Take a look at all the binaries on http://packages.macports.org . MacPorts downloads from here. If MacPorts is compiling from source, you're either using a non-default varient, on a very old version of OS X (MacPorts supports Tiger, but doesn't build binaries), or have some other unusual configuration opt…
That can't be true. For any mildly complex application I install it asks for "xcode-select --install". I'm using an intel Mac on 10.14.6, so it is pretty standard. I just reinstalled the software under a year ago and redownloaded macports from the website and installed it. It seems to require a local compiler to be installed for most applications, such as gcc or llvm. For instance, why wouldn't installing ffmpeg just…
Does the list change if you specify the +gpl2 varient?