I do think the Patriarch had a bit more personal information to go on about you than the average fortune teller.
But HECK, I could give a TBM a Patriarchal Blessing . . . just assign them to the tribe of Ephraim, tell them they were born of goodly parents, talk about serving a mission (for a guy), marriage in the temple, reading the scriptures and raising your kids in the gospel. Then predict leadership or callings, but don't go overboard (don't tell the kid he'll be the next Prophet or that he'll die and be raised from the dead in Jerusalen . . . alongside Glen Beck). And include a bunch of exhortations to keep the commandments and read the scriptures and seal them up to come forth on the morning of the first resurrection. Whiz Bang BAM . . . and THAT's a patriarchal blessing.
Only Ephraim? Boring. A missionary friend of mine was in the tribe of Benjamin. His patriarch had given blessings to members of every tribe. Just trying to speed along the second coming I guess.