What do you mean when? Finding a usb cable that can meaningfully connect your pc and monitor is difficult. Especially in the “grab a cable from the drawer” types of situations.
Not much harder than finding an HDMI cable assuming the USB has a marking.
Especially if faster USB ever gets mainstream and higher spec cables become more common.
If you have a fast USB-C external drive you might be able to use the cable you got for that.
With dedicated monitor cables, they're not good for anything else. Unless you explicitly bought a spare, your only choice is to go buy one.
In the most common case the cable will probably come with the monitor, and one end will just remain attached to it, not much confusion there.
At the moment it seems people use a lot of C to HDMI or C to DP adapters, so almost nothing changed other that the device side connector no longer having a bulky waste of space or delicate microHDMI that always seems poorly made if you get cheap adapters.
What do you mean when? Finding a usb cable that can meaningfully connect your pc and monitor is difficult. Especially in the “grab a cable from the drawer” types of situations.