You're right, COL adjusted salary is a more accurate metric. According to NerdWallet, COL in Brooklyn is ~22% higher than Seattle. If you're looking at Manhattan, you should be comparing Manhattan vs Seattle-Downtown. Living in Seattle outside of downtown is more comparable to living in Brooklyn.
The really lucrative jobs in NYC, are the ones with Hedge Funds that are based entirely in NYC. Places like 2-sigma, Jane-st, DE-Shaw, Jump, and others. The offers they make, are hard to match anywhere else, even after COL adjustments. If you're considering a job at a random NYC tech company though, I agree that the salary may not make up for COL.
The really lucrative jobs in NYC, are the ones with Hedge Funds that are based entirely in NYC. Places like 2-sigma, Jane-st, DE-Shaw, Jump, and others. The offers they make, are hard to match anywhere else, even after COL adjustments. If you're considering a job at a random NYC tech company though, I agree that the salary may not make up for COL.