The thing is that this subject isn't just a "single-issue"; it changes the entire landscape on which understandings rest across a range of key social, cultural and political issues.
How can we address issues of ethnic inclusion if gender policies grossly discriminate against women from minority communities?
How do we address issues of disability inclusion if gender policies discriminate against disabled individuals that require same sex aides for certain intimate needs that enable them to do a required activity?
There are similar scenarios in terms of age and maternity issues.
Again, how can we safeguard children when adults in duty of care positions, such as teachers, are being encouraged to dismiss issues of children and consent?
How do you safeguard refugees if self-declared gender is one of the parameters for appropriate housing? You end up with single refugee females in houses with single host males, and visa versa.
How can we ensure state and healthcare funds are allocated appropriately if certain community statistics are overinflated or underinflated due to a muddying of inclusion parameters? If you have £40k and two sets of proposals: one about a transgender teen health project that proports to tackle some 800 trans-identifying teen girls in a borough, and one about funding a mental health crisis project for transgender adults, it matters how many of those 800 teen girls are just playing out a tiktok teen fad and are not actually gender dysphoric.
It is a basic understanding that the sex of a human body matters on a fundamental level, similarly to age. We do not allow people to identify as younger or older than they are in order to access services and facilities they might desire or to withdraw from certain services or obligations without some form of civic oversight.
But the debate about gender has thrown all this out of the window. Gone is the understanding of the need for some form of civic oversight for radical reinterpretations of basic human parameters.
And that makes this subject an "everything" issue.