Because flash has limits.
It’s slower to write and erase, uses more power, and wears out sooner. ReRAM handles more write cycles, operates at lower voltages, and supports faster switching.
ReRAM (RRAM) is also lower-cost to manufacture. Weebit ReRAM requires only two additional masks, compared to more than 10 added masks for eFlash. As a result, Weebit ReRAM only adds ~5% to the wafer cost, whereas flash adds ~20-30%, and even 40% in some process nodes.
As applications push for speed and efficiency, ReRAM is built to keep up.
Read more in the Guide to ReRAM.