I think they failed to serve their purpose because until relatively recently they've only been present on premium-grade machines, so software couldn't rely on t

I think they failed to serve their purpose because until relatively recently they've only been present on premium-grade machines, so software couldn't rely on the presence of one. Nowadays with Microsoft making it a requirement (as well as fTPM which means the TPM no longer requires dedicated hardware) we might see more use-cases.