I think that part of it is because people searching for investments look for price appreciation and don't pay much attention to dividends.
I only found AGNC by deliberately looking for high-yield stocks, hoping to find something stodgy that paid better than bank interest. I saw the 20% on this one and took a deeper look, saw how long it's been paying that kind of dividend, and couldn't see any reason not to play it.
There still could be one. I just haven't found it. They hedged away the rate-increase risk, and can't seem to keep people from beating down their doors to give them cash. Either it's the biggest scam since Bernie Madoff or it's just managed to stay below most brokers' radar.
I wouldn't risk more than a small fraction of a bankroll on it, but as it goes along and gains more trust it will also gain more share of my portfolio.