non-binary computers?

Except that it isn't base 3, this is how modern modems work. Your standard V.34 modem can transfer data at up to 33.6 Kbps. But it actually uses under 4000 baud. That's because a baud is NOT defined as a bit per second. Rather, it is defined as a signal change per second, and the modem uses a large number of symbols (collectively called a constellation) instead of just binary. The tradeoff is that it can use a narrower frequency band than might otherwise be necessary, but it need a better SNR (signal-to-noise ratio). For the telephone system, which has a hard limit of under 4000 Hz (typically 3300 Hz), this tradeoff is obviously worthwhile. But for other transmission media such as coaxial cable or radio, it's usually better to use fewer symbols and more bauds.