I think it depends on the structure. If you build a room on a raised platform the walls will remain at ground level with the interior flooring still raised to the height of the platform. This can make placing doors/windows tricky and you’ll have to build additional platforms to act as a staircase. Whereas a foundation will raise the ground level of the room. ETA: You don’t necessarily need to add a series of platforms you could add an exterior one as the landing for a staircase, but it will ultimately eat up exterior wall space regardless which option you choose.
A pro to platforms is that they can be connected at varying heights, which is something that can’t be done with foundations. A con is that they cannot be connected to foundations in the same way different height foundations can’t connect.
From my own use of platforms I will only use them in outdoor structures that don’t require walls. If your structure is walled you would be better off using a foundation since the room elevation in conjunction with the ground won’t change with platforms.
Platforms also do not allow pools. This was said above but just to reiterate it. I find platforms best used in conjunction with foundations as a way to raise/lower the interior sections of the build while the exterior is raised with the foundation tool.