It’s really not a silly question at all. Several makers make saws with 20 TPI. Now that’s generally a silly thing. Most people cannot sharpen saws that fine because the teeth are too small. On thin steel the problem is exacerbated the more; with such small teeth and then thin steel, a tooth disappears in half a heartbeat.
You don’t need teeth smaller than 14-16 TPI. These can be sharpened comfortably unaided except for prescription or reading glasses normally used. Saws with 14-16TPI will readily cut dovetails all day long with no issues in general. One problem I come across with thinner plate saws is that the tend to buckle in some hard woods when you saw stock thicker than 1/2″. That never happened with older saws such as Disstons, Groves and Spear and Jackson and several others. Saws made by Thomas Flinn are made from good steel, good wood and good brass. The are resharpenable and though they may not arrive ready to go, they can be made into a good saw with 30-minutes of fettling.