Actually, FPGAs are a mix of everything nowadays. They have both programmable logic consisting of LUTs and flipflops in CLBs with integrated carry chains, connection boxes and routing switches, configurable SRAM blocks known as block RAM or sometimes UltraRAM, DSP blocks providing configurable arithmetic units, PLLs, conventional ARM cores, memory controllers, high speed transceivers and finally also VLIW cores for machine learning inference. Notice how a lot of the silicon area is actually taken up by hard silicon that can be connected to the programmable logic. The problem with the largest FPGAs is that you will reach the point where you are swimming in LUTs and the chip are is better spent on e.g. more memory or other hard wired logic like a processor core.