Reducing a PhD program to 4 years can help but in many fields this is still a problem. For many fields and form of absence of leave can be the end of your academic career. If I recall correctly the average PhD graduate is still 26-27 years old. Which doesn't help much too much even though the average US grad is 31. For many field though this would help a lot. In tech and stem not so much. I remember some of the female faculty I knew telling me exactly how and why so many women end up filtered out. Simply because they wanted to have a child and by the time they came back their research was outdated and their works published by others. They themselves never having children. It's why many women often leave academia for industry jobs.

I personally believe how we conduct research and academia is outdated and does not allow for the proper inclusion of women. And does not allow men to be proper fathers. Sorry for the long talk.

Edit: Got the average age for PhDs in UK wrong it's mid 30s. Even if they started right at the age of 22 it's a wall they will face almost immediately.