> It could be pinned down more closely to something like a single action that happens quite soon after you press a button

So leaving your webmail open is banned because it will still be checking for new messages three months after you opened the tab without any further human interaction. Likewise RSS readers or really any client which is intended to fetch new posts/messages when they appear.

> It's probably relative to current norms of computer use and what we do or don't automate casually (and thus describe as "by hand").

Which is kind of exactly the problem. A new law would presumably still be on the books in ten or twenty years. Do we expect user agents by then to do only the things they do now, or will they get more capable? Banning them from becoming more capable is the problem.