Piano strings are also detuned. The ensemble sound of a string section also comes from small detunings (and timing differences). I don't see that as a characteristic feature of a synthesizer.
Totally agree on Anna Lapwood.
>"String" sounds are implemented by having two ranks tuned slightly different from each other.
The effect you describe is called "voix celeste" (or just "celeste") on pipe organs. But it's common to have "string" stops without the detuning. These are just open flue pipes with unusually narrow scaling, which causes them to produce lots of upper harmonics and weak fundamentals, like real bowed string instruments.
"String" sounds are implemented by having two ranks tuned slightly different from each other. They're not plugged "into" each other, but they're definitely working together to produce a certain sound.
Anna Lapwood is a very exciting organist. She has the social media skills to build a huge following, enjoys exploring all facets of the instrument in both traditional and non-traditional contexts, and is an exceptional musician.