Are you sure they were talking about UUID collisions in a idealized/theoretical system? If you generate UUIDs using, for example, a random number generator with only a 16-bit seed, you absolutely will see collisions, for much the same reasons as in TFA.
I am regularly concerned about using UUIDs in a public-facing way, since that would encourage people to make "vanity" UUIDs somehow. Requiring some kind of value to be hashed to create the UUID would sidestep this a little.
