By now you are aware of my history with Chase. Perhaps they are giving me the lines from people who don't use their cards enough.
I've never let my cards with them sit, but I've also never paid them interest and they basically THROW money at me these days. My UMP has been basically inactive since I got the CSP awaiting a consolidation (couldn't get everything in fast enough to avoid the fee and have the whole line transferred over while missing the fee for this year), and they threw another $4K at me, I'm assuming, to try to persuade me to go back to using it.
(why care? Well, I get 3x miles if I book on UA with the UMP, and since the fee was done for this year and I may end up paying for a couple of flights, I figured I'd just keep it active and use it for those things until next winter.)