Sorry, I should have been more clear. I'm assuming a shared database. So cascading deletes would be defined in the table's schema. Let's pretend we're using Postgresql:
The original position being argued though was "... where all services talk to the same database... You need to split the database up and denormalize it.".
So the basic premise is that there is no shared database, and thus having the database enforce cascading deletes is not an option.
\d Person
[A bunch of table schema stuff]
Referenced by:
TABLE "Billing" CONSTRAINT "billing_id_fk" FOREIGN KEY (id) REFERENCES Person(id) ON DELETE CASCADE
(I typed that off the type of my head so it might not be quite correct.)