You can’t ’compete against yourself’ as you age. You slow. You need to compare yourself to others in your age and sex category then. And actually, to do that well, you need to know where your relative position was when you were younger. To do all this, you do need to know the other women in your age/sex category are female women.
if someone is genuinely not interested in all that stuff, then there are plenty of running clubs that do social runs.
Parkrun has set itself up as an informal race. Lots of people go because of that competitive and comparator edge. Most people who enjoy races know they will never win. They still want to know they are competing fairly and they still care about their position. The only people I know who don’t understand this, don’t race and usually are not runners. And frankly, I think they should not be opining on a sub culture they do not understand. ( I do wonder what these people also do in their spare time, tell Hindus they are doing Diwali wrong?)
It’s nonsense that Parkrun are not doing this because of the fairness to women angle. Parkrun has grown enormously whilst operating as an informal race. That very clearly has not been a deterrant and has attracted an awful lot of runners.
I personally wonder if allowing people to choose to be recorded under either sex or GI is the answer? There are surely enough trans allies that would choose GI to mean not all in this category would be trans, at least in the cities.
(And on a point of accuracy, at its roots, parkrun was run largely by pretty elite male runners, as can be seen by the average finish time of 22mins back then).