or can't play back at real time a fully lit final model with deformations and cloth and what have you (personally I haven't seen anything that can do that outside of a canned softimage demo) seems a little silly.
Just for info, interactive simulation playback
] is existing feature in Maya or Softimage, i think also in Blender to some extent. Of course this depends of complexity of simulation, engine and so on. Some forms of automatized under-the-hood simulation and caching, are traditional part of 3d apps (if ‘simulation’ means calculation based on result of previous frame) like IK solvers on more than two bones (while usual 2 bone ik chain is not, as it could be based on plain triangle formulas).
Anyway, I think, no one said ‘unusable’. Let's say that slow animation
playback does not help, in any way. For small reverse example, Creation Graph in 3d Studio Max can do beautiful results, but it can not compile automatically in Houdini way, so not that much of good reputation in start, when it comes to Max's MCG.Simulation
playback is off-topic here, IMO.
If ‘softimage demo’ was a Syflex example with female dancer, exactly this one can't do interactive playback, Syflex is very external plugin. While ICE can go interactively, as well as some plugins, MtSpring and such.