When ShowOnlyPricing is set to true, the pricing control is forced to only show pricing information for the item. Quantity input and Add to Cart button and functionality is hidden.
In addition features of the CatalogPricingControl such as quantity breaks (ShowQtyBreaks as false), accessory selection and SKU Selection (EnableSKUSelection as false), and the Tabbed Interface (UseTabbedInterface as false) are also disabled.
Implementation Note:
By rule, if pricing is set to be hidden when add to cart is disabled, and ShowOnlyPricing is true, pricing will not display since the property setting disables add to cart.
This setting is found in the Management Console in Site Manager > Catalog Configuration in the Price Settings tab.