As?

In what sense is Lawrence Block writing
'as' Jill Emerson? Writing As someone, I would have said, requires an intention to deceive, or to pretend to deceive, and isn't compatible with putting your actual name on the cover in even bigger letters.
Differentiated from the common "Ruth Rendell writing as Barbara Vine" in that RR did in fact put those books out first with only the Vine name, revealing all later: "Getting Off" is specifically labelled FIRST PUBLICATION ANYWHERE.
So why?