The reason why the gRhasta As’rama comes in the way of mOkSa, is that you cannot abandon dharma in the gRhasta As’rama.
You have to protect and practice dharma in gRhasta As’rama.
If you are attached to dharma, you can’t abandon kartRtva. They go hand in hand.
Only when you are ready to leave your dharma As’rama, can you accept sannyAsa – the mOkSa as’rama.