So, if you are running that website and decide to call your supplier at 11pm at night to resupply something that is selling very well, he damn better pick up the phone right?
There is a reason why 9-5 exists. Its to be productive, its so everyone at the same time is known to be available.
When my client calls me, he expects me to pick up between 9-5 or return his call during that short period, not the next day.
When I in turn in to call a supplier, its the same thing.
My technicians I send to work, do not want to be called in at all hours of the day and week because a customer has put her kids to bed and decided tonight's the night, lets to the job from 10pm to 2pm.
The 9-5 is not necessary for everyone. I agree. But it gives a certain normalcy, expected schedule to most people which allows them to schedule around it and plan ahead.
If the women want to be free of that, then start a web business that allows you do run your own hours.
There ARE options. Not every job has to cater to everyones needs.