Why are "fetch streams" in JS not suitable for measuring data transfer progress?

Jake Archibald's article explores Fetch Streams, a new API in JavaScript that provides a revolutionary approach to asynchronous network operations. He begins by explaining what Fetch Streams are and how they differ from traditional data fetching methods. He highlights that while Fetch Streams might seem ideal for working with large data sets, they have their limitations, particularly related to managing progress during data retrieval. The piece argues that quick access to data isn't always the most critical aspect, but rather how effectively we can manage that data. Jake also underscores the differences in applications where Fetch Streams could be beneficial versus those where they could introduce confusion or delays.