SBC consists of more elements than required to act as a Server or Miner.
Can you agree that? This is the reason Compute Modules do exist. They have less parts on it but all features as long the carrier board covers the I/O

So let's say the same computer as SBC costs 120 but as Module only 57. Technically the same just minus all the connectors and less production costs and complexity.
And now you put all of them together on a single carrier (28 in that case).

From our experience larger CPU's scale badly as they consume more power than several small ARM SBC's. And if we take now the overhead of unecessary parts out of the SBC's, than we get a point of Ressource saving / less impact on environment / less costs / less power consumption / flexible availbility on the market / and scaling means also scaling based on users pocket.