'Intersex' is a very old-fashioned term now.
It used to be common to call people who suffered from spasticity of their muscles 'spastics', for example, people with cerebral palsy. There was 'The National Spastic Society'. It is outdated now and considered unkind. The NSS is now called SCOPE to specifically remove the term 'spastic' from the name due to this change of terminology.
Intersex was revived for a political cause - to try to erode the idea that there are only two sexes and that sex is somehow incredibly complex. Articles in Nature also pushed this idea.
Biology doesn't really care for politics, though, and people who have DSDs have asked not to be called 'intersex' as they find it insulting, as it implies that they are somehow neither or between male and female. It is inaccurate.
I do find it interesting that the people I know who use 'intersex' would consider themselves to be progressive and terribly kind.