I guess that would be a normal byproduct of Google Groups
usurping all newsgroups as if they are all hosted by Google Groups
and of not allowing crossposting between domains. Thank goodness
for that limitation, but some people are going to try to bypass that.
A popular misconception on spam is that it has to be unsolicited
commercial email past some threshold that might be used as a guide for
automatic removal or other action by an ISP or spam filter.