Grapher made a lot of progress because of the needs of the network analyzer project.

It ended up in old fashioned C++ using Cinelerra's toolkit, so Linux only.  It was overkill to bother with the language soup required for mass distribution or rigging something with gnuplot.  Filesystem access from browser javascript is hit or miss.  Interpreted languages have continued to be super slow in parsing large files.  

Parsing & graphing binary data ended up being the focus, although it also parses text files.  It was easiest to configure a row & column range from command line arguments & have a minimally interactive GUI for zooming in on points.  Drag on it to scroll.  Mouse wheel or cursor keys zoom.  Click on a point & it gives the byte offset in the file & the values.  It's a huge improvement beyond spreadsheets.