Yes, there are advantages to writing by hand. Aside from granting a vastly different writing pace and mood for a new perspective, erotica authors would allegedly masturbate while writing. I have no idea if OCR softwares are good enough to cut out the labour required to digitise it, though.
The answer is because chlorine gas is surprisingly simple to generate, but danger is based on proximity. Usually only the person mixing the ingredients would face any lethal danger. The reaction is Cl(-) + ClO(-) + H(+) -> Cl2 + OH(-). However, the reagents are extremely cheap and available at any Walmart, as well as probably in your house already under the kitchen and/or bathroom sink. 10USD can be enough to give moderate to severe eye injuries to dozens humans if used strategically.