Article 6 is the free-movement side of the bargain. Once a product or service complies with this Directive, a member state cannot refuse it market access, or restrict its supply, for reasons connected to accessibility requirements. The article binds member states, not economic operators. For a business it is a market-access protection: a national rule that goes further than the Directive must survive Articles 5 and 6. For an enforcement authority it is a limit on what can be demanded of a compliant good.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.