Its not from family members but from name extraction. If the Church reduces baptism to names submitted by family members, they will be closing temples.
Actually, they get very few names either way. What they mostly do is name recycle. You will very rarely, if ever, be doing the work for a name that has never been done. Which is really amazing when you consider how much effort and sacrifice goes into temple trips outside of Utah.
Genealogical researchers haved used LDS resources for years. In exchange, the LDS Church kept whatever names, places, and dates they didnt already have.
I just posted the comment below on "to dunk or not to dunk" but the question seems more appropriate here.
I had a calling once (20 years ago, I'd guess), where I was some kind of extraction clerk. I would enter data from shipping logs to get names. Didn't they have geneological centers, where they read microfiche in wards houses, too? Do they still do this?