There's only one type of consistency in the CAP theorem. The OP is probably just inexperienced with NoSQL databases since Cassandra, Riak and HBase all support strongly consistent operations.

...over a single key, which is an extremely limited guarantee compared to what a lot of applications need. I'm aware that Cassandra offers a limited notion of linearisable transactions, but last I checked they weren't all that great in terms of functionality or correctness - that may well have changed in the last year or so, of course.

But there is a second consistency he could be talking about, ie ACID consistency. Thus the article...

Let me clarify then. Strong consistency = ACID consistency.

If I write the data and then immediately read it I will get the new data under all circumstances.

And ACID DB solves a tiny fraction of consistency issues.

Most of the really difficult problems show up when you have multiple users and still need consistency.

Granted, ACID databases make solving most of these far simpler.