SQ has the same two “fully featured” device network limitation built in. I am not sure about the QU system, but I suspect there is a similar restriction. The SQ allows for more “single buss” devices, but caps out the total devices at 8 (including the two fully featured devices). The Avantis and DLive systems also have a hard limit, but it is so much higher that it really isn’t a problem for 99.999% of the use cases (I think it is at least 35 devices on each system).
I don’t know why A&H builds this into their devices, but given the fact that they seem to have made a conscious decision to handle it this way, I doubt we are going to see this limitation change on the CQ (or any of the A&H systems).