1) Most people DON'T do this and thus don't know their own set of unconcious tells. There's also a treasure trove of samples on this site and other mafia sites across the internet. Very few people bother to analyze them all thoroughly because of the work required. That doesn't mean the method is bad if it's done in a good way.There are people on this site that will analyse their posts in excruciating detail to see what words, sentence length, post length, spread of topic, and lines of questioning to see what they do naturally as either alignment. And then they will draft their posts multiple times until it perfectly represents their town meta specifically to fuck with meta tells.
2) A competently written program (with varying amounts of human guidance depending on how it's coded) still might be able to find some unconcious tells that a player doing your cited "muffin" process might have missed. Things would be different if both sides put in the same amount of effort, then things would be more interesting. Then I would have to switch to other methods or try to code something even better. This arms race is actually easier for town though since I have to identify unconcious tells while the scum player has to identify which unconcious tells I've detected and try to correc them. However that's not the case right now since most people DON'T put in that type of effort.