Throughout history ‘mistress’ was a term with a multiplicity of meanings, like so many forms of female address. In his Dictionary of 1755, Samuel Johnson defined mistress as: '1. A woman who governs; correlative to subject or servant; 2 A woman skilled in anything; 3. A woman teacher; 4. A woman beloved and courted; 5. A term of contemptuous address; 6. A whore or concubine.'
Erickson’s investigations have revealed that ‘Miss’ was adopted by adult women for the first time in the middle of the 18th century. Before that, Miss was only used for girls, in the way that Master is only ever (today increasingly rarely) used for boys. To refer to an adult woman as a ‘Miss’ was to imply she was a prostitute.
The introduction of Ms as a neutral alternative to 'Miss' or 'Mrs', and the direct equivalent of 'Mr', was proposed as early as 1901.
https://www.cam.ac.uk/research/news/mistress-miss-mrs-or-ms-untangling-the-shifting-history-of-titles
So, if we can move from Mrs and Miss to Ms, why do we still need gender specific titles?