Why would San Francisco fans want to watch a farm team for a San Jose franchise? Why would the Sharks want to pay premium rent to play in a premium place that probably won't be that hockey-suitable?
Why would anyone try to use an arena in Oakland that isn't suitable for hockey in the first place (NOTE: I know about the Golden Seals. You may not be aware of the renovation.), much less due to be turned under for a new development? Oakland isn't exactly inexpensive. Oh, BTW, you're asking them to be a San Jose farm team, too.
The real question to ask is why San Jose didn't work to get Stockton in the first place. It's possible they were helping Calgary solve their problem, perhaps, but that's always stumped me a bit.
I'll leave Sacramento out of it , except to note that Hutch's response regarding the basketball affiliation going to Stockton was amazingly impressive in getting almost everything wrong in a relative economy of words.