As someone who used to program for Palm OS a lot, I was pretty happy to see this name. :)
At first I was very skeptical that it would find any meaningful bugs, but in fact it was very good at finding memory leaks and edge cases. In the end it took us several weeks to finally be able to survive the 1M gremlins without a crash. A single run of 1M gremlins would take about 24 hours.
In later years they added the capability to supply your own dictionary of values to apply to certain inputs so that gremlins could get past validation, and it would also save the entire state of the device every 10K events so that you could easily reproduce errors that Gremlins found.
I could definitely see this as a good way to stress-test certain parts of your app, though it takes a ton of time, and frankly without surrounding tooling (like resource monitoring, saving "state") it wouldn't be practical.
Fuzz testing, on the other hand, is about modifying the data, to interacting with the UI. To use an analogy, fuzz testing Microsoft word might involve corrupting various structures in the DOC or DOCX file or in an OLE embed with malformed data and seeing how the parser/program reacts. The Gremlin.js equivlent would be just clicking on a bunch of buttons in the Word UI really really fast.
Both are helpful, but they are testing different things
Fuzzing is not about modifying data. I don't think that's the right way to describe fuzzing.
It's about testing the durability of a program by trying all kinds of data, as greedy as possible. This includes known problematic inputs and random inputs to match some expectations. By random it can either be totally random (any length, any pattern) or protocol-aware.
Random clicking is a form of random data testing because you are trying random input stream to a program. Your argument is not entirely wrong either. By fuzzing his UI he may trigger the browser to crash. He may trigger his monkey to crash. Fuzzing is a very general technique. I can write a fuzzer that fuzz Firefox's UI Australis. What will I look for? Maybe after opening 100 tabs and closing the 45th tab the titlebar disappeared. Or resize the browser from range s to range w I will find some range will cause the UI to look ugly (style overflow, etc). Or after clicking on the scrollbar several times consecutively the browser crashed.
Barton Miller, the "Father of Fuzzing" did UI fuzzing by simulating actual keystrokes and mouse clicks. See ftp://ftp.cs.wisc.edu/paradyn/technical_papers/fuzz-nt.pdf
In his Forwards page, he even mentioned "Monkey" http://pages.cs.wisc.edu/~bart/fuzz/Foreword1.html
Relating to the practical example: if one is trying to find bugs from the UI code (or it is the only way to feed inputs to the program), monkey method of fuzzing is the way to go. But if one tries to test the deeper layers of the program, it is beneficial to try to find the lowest layer of inputs we can access, since it enables faster input of test cases and thus makes the fuzzing more effective.
One way of the other, my opinion is that both are fuzzing, by the definition I gave for it :-)
I'm not sure how up to date the CVE list is, but it probably gives you an idea, if the fuzzing is still relevant or not :-)
Andy Hertzfeld: http://www.folklore.org/StoryView.py?story=Monkey_Lives.txt
They want to break as many things as possible while keeping uptime and that sounds freaking awesome! :D
(Watch out for water.)
Relevant doc: https://github.com/marmelab/gremlins.js#configuring-gremlins
I guess 40-something.