"Unsuitable" meaning it's not a great choice. Yes, it's been done
a lot (whether or not you can really say "to great success" is another matter, I think).
What I mean is that I think using Java meant the company was required to spend more resources than should have been necessary to accomplish their goal.
BTW, when I say "Java", I mean the language, not the platform. Java-the-platform is very suitable to business software. Java-the-language, less so. Java OOP brings with it a ridiculous amount of incidental complexity, boilerplate, and impedance mismatches. Of course you can make it work, I do it every day. I just think it's a poor choice. It's certainly not the worst choice, and the platform + available libraries is definitely a plus.
And as I mentioned in my original post, there are way to make it more suitable through various hacks (like Lombok) and libraries, but other languages are more suitable out of the box (including other JVM languages).