The strategy of Phi isn't bad, it's just not general. It's really a model that's meant to be fine tuned, but unfortunately fine tuning tends to shit on RL'd behavior, so it ended up not being that useful. If someone made a Phi style model with an architecture that was designed to take knowledge adapters/experts (i.e. small MoE model designed to get separately trained networks plugged into them with routing updates via special LoRA) it'd actually be super useful.