Who still needs ISBN in the digital era?

My question is this: with e-books now the norm, why should even one bother with ISBN or want to have one? Dump the ISBN system once and for all. How about creating our own system? Just because a system is developed in Europe does not mean it’s good for us or is needed.
A sample of ISBNs used by publishers. The New Times/Courtesy
A sample of ISBNs used by publishers. The New Times/Courtesy
Times Reporter