May I ask if this was before or after GLB (1999, for the kids following at home)? (My experience as a derivative market maker was post GLB and post crisis.)

Managing a flat book is less exciting than placing directional bets. It’s also less profitable, at least when the bets go well. Add to that the complexity of market making, particularly when derivatives enter the equation, and you get the two decades–following the advent of ECNs, turbocharged by GLB and ending in the financial crisis—in which market making desks were proprietary traders first and liquidity providers second.

Also, if you buy a swap and I simultaneously sell stock, there is both a simultaneous trade and liquidity being provisioned in a value-adding way.