"It's a pipeline problem."
No, it's not.
You're just not doing enough work to discover talent from underrepresented backgrounds.
It's not a pipeline problem.
You just have homogenous networks and you don't feel comfortable interacting with individuals, groups, and organizations whose specific aim is to help people from underrepresented backgrounds find jobs.
It's not a pipeline problem.
If I were a sourcer, recruiter, hiring manager, or anyone who plays a role in discovering talent from underrepresented backgrounds, I could reach out to about fifty people in my network, asking very specifically who they can connect me with so I can very intentionally find talent from underrepresented backgrounds.
It's not a pipeline problem.
Your biases and prejudices and assumptions – both unconscious and conscious – have led you to rely on the "it's a pipeline problem" narrative.
It's not a pipeline problem.
If you truly cared about creating more diverse and inclusive teams and companies, you would do your part. You would try harder.
You would make it your stated aim to diversify your talent pools. You would stand firm on presenting diverse candidate slates. You would leverage the myriad of individuals, groups, and tools available to you.
It's not a pipeline problem. Do better.