> Is there a technical reason for it like causing interference or something? That's correct, more or less. There's this thing called "frequency shift keying"

> Is there a technical reason for it like causing interference or something? That's correct, more or less. There's this thing called "frequency shift keying" (FSK) which was the de facto standard digital modulation technique at the time the regulations were created. With FSK, you transmit data by toggling back and forth between two frequencies. That abrupt jumping back-and-forth creates hellish interference for people trying to use nearby frequencies. Today, the obvious solution is to limit bandwidth so that there's a healthy amount of space for people to avoid that interference. However, in a (1970s/1980s) world where FSK is the only widespread modulation scheme, that wasn't really the mindset. The way they saw it was simpler: "higher baudrates demand more bandwidth, and more bandwidth creates more interference." Thus, they regulated baudrate as a means of regulating bandwidth. The impetus for the rule change is simple: we have better modulation techniques nowadays. In case I haven't bored you to death, the simplest one to explain is probably GFSK. It's similar to FSK, but instead of abruptly jumping between the two frequencies, you gradually slide back and forth between them (the "G" stands for Gaussian). GFSK requires more precise electronics, but it doesn't cause as much trouble for people trying to operate at nearby frequencies. There are countless other modulation techniques as well. Bluetooth is probably the most notable implementation of GFSK (though modern Bluetooth actually uses something else). For completeness: FSK is very useful and it's still widely used today. Your garage door opener uses it, among other things.