I didn't say traders don't exist. Simply that they don't make discretionary trading decisions in the way that the word 'trader' might imply. Of course there are exceptions to this - a lot of options trading still involves discretionary traders.
The job posting you linked to is responsible for making sure that execution trading systems are working as they're supposed to - it's mostly an operations role. Similary, traders exist at Citadel Securities but they're mostly making sure market data is coming in correctly, orders are going out correctly, etc. Except in options market making.