We had an SNES hooked up to the antenna input for the simple reason that if you're a kid who wants a TV in the attic, away from adult interference, it's not going to be a brand-new model but a hand-me-down from the living room.

Still we programmed channel 1 to the SNES's frequency so we wouldn't have to switch channels after turning the thing on. On the console side though composite outputs quickly became ubiquitous as including them involves little more than bypassing the RF encoder. Speaking of the ZX Spectrum.