It's been a technical limitation. DOCSIS 3.1 and below allocate certain frequencies to download and certain frequencies to upload. There's a lot more allocated

It's been a technical limitation. DOCSIS 3.1 and below allocate certain frequencies to download and certain frequencies to upload. There's a lot more allocated to download because of how people typically use the connection. DOCSIS 3.1 moves to a more flexible channel structure that allows for high-split systems. Xfinity has been rolling out 75-200Mbps upload speeds with their DOCSIS 3.1 network, but DOCSIS 3.1 is still lacking for gigabit symmetrical connections. DOCSIS 4 mostly removes that limitation and allows for the full amount of spectrum to be used for up or down.