[AccessD] Subdatasheet vs. Relationships?

I have inherited an A2K database that has numerous tables related to
one another via the SubDatasheet property. Make no mistake, I hate
this feature with a passion because it slows databases down. 
However, if there is a legitimate reason to use it I'll buy in.

The db has no relationships defined in relationships view. In the
mdb is a main form based on a single table (no JOINS in the
RecordSource), with several subforms on tabs. Each subform is
getting data from a single, distinct tables (that is, no two subforms
use the same table for data. All subforms are linked to the main
form by BlahID.

Now, for the life of me, I can't figure out what using the
SubDataSheet property of the tables does to help this application. 
What gives?

-Christopher-