So this is my current hypothesis on the bans (copy-pasting):
"This assumes they aren't banning everyone at the same time and that they'll do so in waves.
The spotpass "send info" option is automatically on straight from the initial console setup (when you accept TOS), and many people don't know it even exists.
Others were banned without it, but it seems to be the biggest factor.
So the other factor needs to be something *fewer* people trigger, and the friends list "share currently played title", as I was told, is opt-in (it asks you if you want to); it also requires you making a mii and going to the friends list.
So if these are the factors, it makes sense that the former has a significantly greater impact.
Both factors technically make sense as they both seem to send the title IDs of what you installed to the servers."