I haven't sown seeds directly into neat perlite but I have taken cuttings!
All they need is sterile medium that holds moisture and perlite does that quite well.
Think of it this way; Lots of people chit seeds on a piece of kitchen towel what is the difference?
The paper acts as the sterile medium that holds moisture.
In the case of seeds the endosperm takes care off everything until the roots/cotyledons break out of the seed shell /coat.
All you have to do is supply the necessary moisture and temperature.
I agree mostly when gray mentions
"guess that at the start all they need is water, which the perlite will hold better than soil?"But getting sterile soil might be a bit more problematic!