A ridiculously large number of people use Matlab as a tool. I can't think of a single engineer that doesn't curse its name regularly but I've yet to encounter any actual applications written in it.

It's Excel for engineers.

I have seen people doing amazing and complex things with Matlab, including fancy GUIs and stuff. But it is almost exclusively used for internal tools as far as I know.

I think this often happens anytime there is a large amount of legacy software written by folks that had software has a tertiary skill on their tool belt.

The Matlab IDE is not bad though and is a lot like Python's Spyder IDE. Also, a lot of Matlab commands have fully browsable source provided I've been told.