Nit-picking and pedantry is toxic in real life and on message boards, however it seems to be ever-present in communication with fellow software engineers. In software engineering, if you miss an = sign or misplace a { or use a single wrong keyword in a 100K line program, the program can fail spectacularly. Debugging a broken program often involves nit-picking syntax--it's an essential tool in a software engineer's arsenal.
This is not universally true for written argument or rhetoric. Being clear is good. Using correct grammar is good. The details count. But attacking a clear, articulate argument by nit-picking grammar or word usage is pointless and does not substantially add to the conversation. Despite this, this behavior seems to exist as a cancer everywhere on the Internet where you encounter written argument or persuasion, including here.