Keymod and mlok are the evolution of rails like the one you posted. They offer more modularity because multiple companies are producing accessories for them as opposed to being stuck with whatever the specific rail manufacturer offers. Typically, proprietary modular rails have a very limited selection of accessories available and usually require that you mount a small picatinny rail section to add any accessories. With mlok and keymod, the accessories direct mount to the rail, skipping the need for an additional picatinny rail section. Saves you money and weight.