Sure, but analog processing happens continuously and at an SNR that is equivalent to a very high bit depth. If you had an analog processing chain with 18MHz of BW (which granted you'd need somewhat more GBP), that would be more akin to a digital system that can produce output samples at 40Msps+. If each output sample needed even just a few dozen processing clocks to compute, you're already looking at a 500MHz+ clock. Although you could build that digital solution, it wouldn't surprise me if the analog solution was significantly lower power.