Each country probably had the others do the dirty work in their own country, a legal loophole.

I think they don't care if it's illegal. They believe their actions are justified. The primary problem with that assumption is that they are the ones that justify it.

Agreed, it's just that there's no tribunal to bring the case to.

So does it set a precedent that the humble citizen is able to do it without legal ramifications?

In a sense, yes. There will be ramifications, of course, but they are entirely extralegal.

It's best not to think of the Five Eyes as being nations of laws.

Seeing this intelligent if pessimistic post downvoted without comment makes me sad for Hacker's News.

Illegal they do right away. Unconstitutional takes a bit longer.