The 'rivalry' as it is.... always existed for me for a simple reason... I live in Niner Country. (I've posted about this before).
There was the LA vs SF thing, geography, but since I don't associate with either place that never meant much to me.
Rivalries, for me, came about by 'big games'... combined with being 'good games'... So the Vikes, Cowboys... some others. But SF? So few and far in-between that I never saw the Niner's, and still don't, as a true rivalry except as a 'concocted one'... legitimate, I'm not saying it's not... but a shallow one.
When they moved to St. Louis I always found it odd that the 'rivalry' not only survived but may have deepened..... since geography was no longer a factor I was surprised by that. Again... not saying it wasn't legitimate... but the 'reasoning' was a bit odd to me.. until, of course, the consecutive losses thing grew so intolerable.
Now I hope no one reads this and jumps to the conclusion that I don't very much dislike the Niners.. my dislike for the Niners probably runs deeper than any of you. But again.. this 'rivalry' has always been, from a football perspective, the most 'weak' rivalry of the more notable rivalries in the NFL. - JamesJM