They don't always use Catalysts. Thrashers are common too.

You know, it really grinds my gears when minmaxers yowl at me and accuse me of badfits because "blah blah ship strength pigeonhole pigeonhole pigeonhole". One of the players I supplied the procurer fits to came back to personally thank me after he used it repeatedly in lowsec to the point of making at least one ganker raqequit. Look at the jamming strength: all ewar focused on a single target gives you a minimum of 8.8 points of ECM. Add the amplifier and some skill enhancements and you can get up to 12 points or more which can be spread across multiple targets if needed. That is not a bad fit, that is you being ridiculously inflexible and refusing to get creative. Indeed, I have lost many ships, many of them badly fit, but I learned from those fits. I learned that racial bonuses are not the be all and end all of ship fitting. I learned that many EVE players are either clueless about module stats or completely rigid in their thought and design. I learned that such cluelessness/rigidity is exploitable. And thus, the ewar Procurer was born.

'Godlike shield tank' won't save a miner because CODE fits their destroyers for maximum alpha damage rather than DPS; they know they will only get off maybe a dozen volleys at most before they are concorddokkened, so they sacrifice every other attribute to make those shots count. Successfully jamming a ganker shuts down their targetting scanners AND KEEPS THEM FROM TACKLING, SCRAMMING OR SHOOTING. THAT IS THE WHOLE POINT.