I don't think that's entirely true. The Rams left because their owner (the widder Frontiere) was a native St. Louisan who wanted to bring football back to her hometown after the "unfortunate" demise of her sugar daddy. I don't know what their attendance was, but I don't recall that they left because they couldn't get enough fan support. They, and the Raiders, were frustrated by a problem in getting a modern stadium built in LA. The Rams were playing in the Rose Bowl and in Anaheim, neither of which are good venues for the NFL. The Raiders were playing in the Coliseum, which, like the Rose Bowl, is just too big for NFL games. All those empty seats in a 100,000 seat stadium where the field is too far from the seats because it was built for track and field. They tried to get stadium deals, and just gave up.
Now, the new Rams owner has a deal in place for a stadium at a great location, and it looks like a go. That changes everything about football in LA. The only question is, would he be willing to let the Chargers play there? (What do you want to bet the Chargers try to make that a condition. What do you bet the NFL doesn't).
Were I voting for the interests of the NFL, I would let the Rams move back to LA, by themselves. I would sell a franchise to St. Louis, or allow Jacksonville or some other lame franchise move there, and I would force the Chargers to stay where they are. While LA can support a franchise, I am not convinced that they can support two, especially if they play in the same stadium. Spanos bought a San Diego team, now he thinks he's Al Davis and can just move wherever? He can't. Enjoy your millions, Dean, and give up on LA. You are not capable of handling LA.
Respectfully, the only time the Rams played in the Rose Bowl was in the 1980 Super Bowl.
FROM WIKIPEDIA:
Los Angeles Rams (played at) the Los Angeles Memorial Coliseum between 1946 and 1979.... Anaheim Stadium in Anaheim from 1980 to 1994.