Simulation models of electronic components, especially analog and mixed signal ICs, are scarce and more often encrypted and locked into the manufacturer's chosen proprietary simulation software(e.g. Tina-Ti and LTSpice)

There exist many good circuit simulators, including open source ones like ngspice, but every simulator lack many models to seriously simulate any real world circuit boards with ICs and discrete components from multiple suppliers.

As an electric engineer, would you love an open source repository of IC/component simulation (SPICE/IBIS) models?

Why do chip manufacturers lock up their models to their chosen proprietary simulator (which they usually provide for free anyway)

What are the difficulties of having this open source repository?

Is it simply difficulty or costly to develop third party models, or are they limited by copyright, patent etc?