help me understand how socializing something erases the ability to assign value?

When the government allocates services, it does so without reflecting actual consumer demand.

Everyone pays indirectly through taxes or fees so the actual price does not reflect the marginal value of the good to any one person.

When government provides, people lose the direct connection to the good or service so there is minimal incentives to moderate usage which leads to waste or shortages.

When a government provides services, it does so without individual preferences, just what some suit in an office feels like the public needs.

A government service will only ever be a one size fits all operation as it cannot customize at that large of a scale.