I agree that being relaxed enables growth. The negative consequences come later. Protocols become cultural artifacts with history. You need to study the histor

I agree that being relaxed enables growth. The negative consequences come later. Protocols become cultural artifacts with history. You need to study the history of bugs and 'features' to learn the de-facto standard. To write a good HTTP client that parses and renders HTTP/HTML/CSS/ in the wild from the scratch you need to learn how Chrome, Safari interpret and implement specs. It's possible to write future proof strict protocols with detailed instructions on how to handle new versions, unknown extensions, etc. gracefully.