Because the end result is standard PCM, the quantization can be only worse, not better.
Oversampling ADCs push a much greater quantization noise into the inaudible range, and then, by low-pass filtering, reduce the quantization noise to the level of standard PCM.
Oversampling ADCs are not better, they are much cheaper, because 16-bit or 24-bit quantizers with enough speed and accuracy are extremely expensive.
Oversampling, i.e. sigma-delta modulation, in both ADCs and DACs, allows the use of much cheaper quantizers with low resolution, of only a few bits, or even of only 1 bit, and of much cheaper filters, which do not have to be very steep, without degrading too much the quality in comparison with real PCM conversion done at the Nyquist frequency.