Having an own file format is true for many 3d apps. If DAZ want to use the features 3Delight offers (NURBS,SDS) they cannot use the poser format, since it offers no support for mathematically defined objects. DAZ probably wants to support it's own file format too, they surely will have different prices for Poser and D|S-Products. Since D|S is not really a modeler and supports a rendering engine with more than enough options, I do not see why pushing a closed file format is a real problem - Bryce is a One-Way-Ticket too, Vue used to be one for a long long time.

A ship in port is safe; but that is not what ships are built for.
Sail out to sea and do new things.
-"Amazing Grace" Hopper

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