AFAIK, li-ion batteries can take ripple very well (I have also ran some tests myself for a customer who wanted to test the scenario of 100Hz rectified AC ripple, and within some hundreds of cycles, did not see any worse degradation), so it makes sense not to filter. Especially since the charge rate (compared to pack size) would be small.
Without unnecessary filtering, you save cost of unnecessary components, and easily get unity power factor by just copying the input voltage waveform as charge current waveform.