Of course it has something to do with it. It is the foundation for the hate that many have regarding sexuality outside their comfort zone.
I'm an atheist - have been ever since I was a young teenager. So how do you account for your perception that I am a transphobe?
Would you like to know why I take the position I do? I'll tell you why anyway...
First, the Basis: Sex is binary. This an observable, irrefutable, scientific reality. ALL mammals (including ALL humans) are without exception, either male or female, there is no
"in between sex", there is no third or fourth or fifth sex.
I steadfastly REFUSE to deny observable, scientific reality - on principle - and I certainly refuse to do so for the sake of a few self-entitled men labouring under the mental delusion that they are opposite of the sex they were born.
Second, the Impact: Denying scientific reality in this case leads directly to negative impacts on more than 50% of the population. ALL women (even those who don't yet realise it) will be impacted negatively if transgender identified males are permitted to be granted women's rights. Our mothers, grandmothers and in some cases, great grandmothers fought a long, hard and sometimes bloody battle to escape the subjugation of males to earn the right to their own self determination and equal treatment with and by their male peers... too long, too hard and too bloody for it all to be thrown away on the altar of the gender ideology cult.
Third, the consequences: We are not just talking about bathrooms here, we are talking about about the right to assemble as a group of women to discuss women's issues such as maternity, pregnancy and safety, and not have men intrude on their gathering and attack them for not including them. (this has happened a lot in the UK, for example, when preganancy help and discussion groups have been set upon by transgender identified males demanding they not be excluded.
This happened just a couple of days ago in Brighton, where transactivists trashed a venue that was about to be used for a meeting of feminists.
Consequences also include males trying to force their way into rape crisis centres, women's hospital wards, domestic abuse refuges, women's prisons and women's sports.
Fourth, the personal impact: I have already had my daughters accosted by transgender identified males (well, they claimed they were women but didn't present at all like women) - they used the magic
"Self ID invocation" when their presence was challenged - one in a public toilet, the other in the women's changing rooms of a public swimming pool.
But regardless, you asked "How has society gotten so stupid that this could even be a question?" I can think of an innumerable number of examples of our society and others that were far more stupid. Such as, how did society ever get so stupid to believe in the Bible? The Bible has done and continues to do more damage on society than transgender individuals have ever done. Should we outlaw churches?
The Bible might be relevant to the argument about right wing transphobia, but it doesn't account for the atheists (like me) or the increasing numbers of centre-left (like me), moderate left wingers and liberals who are understanding they are on the wrong side of this debate...
There have been many societies throughout history that have had more than two genders.
None have had more than two sexes... ever!
Gender is a social construction as are laws and regulations. If we are to create such laws and regulations, we must define terms.
Gender is meaningless - it has NO scientific basis. As you say, it is merely a social construct - one that is unique to humans... the decision to abrogate the rights of 100% of women MUST be based on a far greater range of considerations that just the thoughts in the heads of a few delusional males.