It's the only solution that is economical, readily adaptable to existing Fabs and actually ready.
Sure, there's talk or graphene, diamonds, GeSi, etc.. but who has a product that is ready?
Who has a product:
That is compatible with CMOS?
That can be addapted to existing Fabs?
That can follow Moore's Law?
That applies known Silicon scalling processes?
That doesn't over heat?
That has over 30 years of use in industry?
That can integrate electrical, optical, RF, IR, all in one chip?
That supports universal memory?
That has a promising future in quantum computing?