It does worry me because there are a lot of thunderbolt devices that ARE thunderbolt only and don’t fall back to any other form of USB on a PC without thunderbolt… even when USB 3.0 speeds would be more than adequate for the device being used. Or even 2.0 speeds. Just a big fat no, can’t use em at all.The thunderbolt standard requires the port be at least USB 3. If it's only backwards compatible with USB 2.0, it can't be labeled as thunderbolt. It can still be done, just can't be labeled as such.
I don't think anyone even makes a USB 2 only thunderbolt controller chip, but I guess it could be controlled via firmware.
Like the Blackmagic Intensity Shuttle… was sold in both thunderbolt and usb 3.0 versions. Both are equally capable but one has more system compatibility than the other because the Thunderbolt one will not connect to a PC without Thunderbolt at all.
And then there’s the Focusrite Clarett+ 8pre… currently sold in both Thunderbolt and USB 2.0 versions that are otherwise identical 🤦🏻♂️