>The proper EAV normalised structure would have three tables

But then it's not EAV. In this case he is creating a single table to hold all of the attributes. The pros of this model are that once the business decides they also want to record which browser was used, there are no database changes required. In your case, you'd have to spin up a new table (and then another one once they want to store the time, and another where they want to store whether this is a returning customer, etc.)

I'm not suggesting EAV is the correct solution, but the model has its merits... rarely :).