I don't really understand this comparison. Point of having a service is not only exposing computation - more usually, it's exposing a centralized database. How

I don't really understand this comparison. Point of having a service is not only exposing computation - more usually, it's exposing a centralized database. How is library useful in this context? Unless, the author is talking about writing, for example, a number multiplication library vs number multiplication service... but then the advice is obvious. EDIT: also, this stuff about accessing memoty, denying access at runtime makes me think that it was written for a different times. Nowadays, who creates new stuff that's not isolated by VM or container layer?