1- The fact that women are often described through stage directions rather than through dialogue reinforces the submissive role women had in Glaspell's time. Women were under the power of men; they had to "follow" men's orders. This is the reason why they were described through directions; they were not expected to speak or to give their opinions. Therefore, their characters could not be described through their words in dialogues.
2- This submissive and obedient description of women sets and fixes a role of women in society. This legitimises that role , so everyone will expect women to behave like that. If a woman happens to rebel against this submissive role, people will tend to underestimate her reaction and will leave her alone.