Those hubs are from the era where you had to choose "single transaction translator" or "multiple transaction translators" (STT vs MTT). If the connection from the hub to the computer is running at USB 2.0 Hi Speed (480 Mbps), you would expect to be able to connect multiple devices at Full Speed (12 Mbps) and have them all run as fast as they possibly can. But with a STT hub, you can actually only talk to a single Full Speed device at a time at 12 Mbps!
This issue has been known about the whole time, but this important feature (MTT) is almost never advertised so you need to carefully research it. It's very relevant for MIDI because MIDI merge boxes all use 12 Mbps—and so do input peripherals like mice, keyboards, and serial adapters, scanners, etc.
Is it safe to say that all USB 3.x hubs support MTT for USB 1.1/2.0 connections? Google AI says no. Even the latest USB 3.x hubs might not support MTT. Note that the USB 2.0 and USB 3.x parts of a USB 3.x hub are completely separate so it makes sense that some manufacturers might cheap out on the USB 2.0 part of the hub.
Does USB Prober.app show a difference between hubs that support STT or MTT?
Yes, the Interface Protocol for a Hub class Interface has these options:
http://www.linux-usb.org/usb.idsC 09 Hub
00 Unused
00 Full speed (or root) hub
01 Single TT
02 TT per port
USB Prober.app lists those as:
Interface Protocol: 0
Interface Protocol: 1 (Multi TT Hub configured as a Single TT Hub)
Interface Protocol: 2 (Multi TT Hub)
I don't know why USB Prober.app says "Multi TT Hub configured as a Single TT Hub" instead of just "Single TT Hub". The source code doesn't say anything.
Looking at the output text produced by USB Prober.app, I see that any hub that supports Interface Protocol 2 also supports Interface Protocol 1.
ioreg shows which protocol each interface currently uses.
Besides interface class, there is device class.
USBProberV2 source code has these device protocols for device class 9 "Hub":
0: Full/Low Speed
1: High Speed Single Transaction Translator
2: High Speed Multiple Transaction Translators
3: SuperSpeed
Full/Low Speed is for USB 1.1 speeds.
High Speed is for USB 2.0 speed of 480 Mb/s.
SuperSpeed is USB 3.x
Why are device protocols different than interface protocols? Or, why doesn't the USB ids database have a distinction between device and interface protocols? Need to check the USB spec to see what the difference is.
https://www.usb.org/defined-class-codes describes the difference between device and interface descriptors. class 9 is device only, so why does USB Prober show class 9 for interfaces? What document defines protocol 3 (SuperSpeed) of USB device class 9 (Hub)?
Anyway, the combination of device/interface class and device/interface protocol in ioreg should indicate exactly what mode the hub supports and uses.