Based on https://support.google.com/groups/answer/2465464?hl=en and my experience with the user interface just now, it appears that Google Groups restored the ability to directly add members to a group.
However, when I Googled for information about this, I found only articles about the removal of this ability in 2011. Is it really back? If so, did they explain why?
With Yahoo! groups not restoring this ability and groupspaces.com apparently going out of business, I'm once again looking for a new home for my groups.