When downloading directly from iCloud.com that's true (and annoying), but you can also bulk download all of the originals via Photos.app (making sure to check "Download Originals to this Mac" rather than "Optimize Mac Storage").Unfortunately, that wouldn't work for my wife's situation. Her computer is one of those MacBooks with a 256GB drive, and only one USB-C port. So the amount of data stored in her iCloud photos would easily overload her drive, and if I hooked up an external drive, the computer would run out of power before the transfer completed.
I'm not interested in buying a hub for a one-off operation.
I tried afp:// and smb:// mounting Photos libraries on large drives on other machines on the LAN, then downloading the photos to those, but that turned out to be excruciatingly slow, and very unreliable.