We get asked about support for strikethrough frequently. Here are our thoughts on that:
 

Tot is based on plain text with standard Markdown for a limited amount of styling. Strikethrough is not a part of the original Markdown specification and current extensions implement it in different ways (sometimes one tilde, sometimes two, sometimes a library compile-time option, etc.) If the Markdown specification changes to incorporate strikethrough, we'll happily adopt it, but our guess is that's unlikely to happen.