"RAM" here means SRAM (static RAM). That just means "array of storage elements (latches) connected by bitlines and wordlines", which is way more efficient than "random latches we scattered throughout the chip". SRAMs are used extensively for indexed storage such as physical register files, queues, predictor arrays, etc in modern microarchitectures.

Anyway, unless you have a very small array, even addressing is enough to make it slow. And arrays were already big at the time I programmed FPGAs, I can only imagine they are much larger now.