They suggest P4 and DAZ|Studio because it is the only rational thing to do. P4 vs P5 isn't like the differences between software that runs on a Mac vs PC. Say I model and rig a figure in P4. This figure is obviously going to work in P4, but is in all likelyhood usable in P5. If you dig through the available P4 content other than textures on the market (and free) about 95% of it works just the same in P5 as in P4. So should they say their products are for P5, simply because most of them will work there? Most people would automatically read "for Poser 5" as meaning "NOT for Poser 4," and cost them a large portion of their P4 users, who appearantly still outnumber P5 users by a wide margin. Stating that it is for P4 leaves users of P5 with the hope of downward compatability, so they keep their P4 customers and P5 customers.