I have and like both Moi3d and Plasticity - and rarely use both of them. I almost always need to change things later on and that isn‘t easy for both programs - most of the time it is easier to restart from scratch than trying to change an existing design.
A 3d constraint system might be most fitting for history free direct modellers - something along the lines of what Solid Edge does in Synchronous Mode. Imho the first application that gets a proper implementation of 3d constraints done wins the competition :)