Several years ago when I was doing contract enterprise development work for various Fortune companies, EJB was all the rage in the Enterprise Java space. I started to feel a little rate pressure, so figured I'd better at least pick up a book and get up to speed.
About 3 chapters into it, I couldn't believe how bad it was (especially entity beans). I mean, it was almost like the perfect anti-pattern. Anyway, that didn't stop massive numbers of enterprises from jumping in head first, because it was sold as "the way" to do enterprise development. The tooling and app servers were insanely expensive too. But many IT managers didn't want to take any chances on not going the standard route.
Anyway, that about sums up enterprise software. Even for groups not into EJB specifically, the culture and thinking are the same. There is this meme that enterprise software must be more robust or scalable, etc., but the funny part is that consumer facing Web apps must typically be far more robust and dynamically scalable to serve much larger user bases. Enterprise software is typically run in a more tightly controlled environment too (specified required browser and OS, Intranet-based, etc.).
Yet, just labeling something "Enterprise" and targeting it as such, seems to command a premium.
Extremely slow is a function of the interdependencies and the CYA (nobody gets fired for buying IBM).
And the unwillingness to replace is because nobody actually knows everything the current system does, much less how it does it. Projects that have 10+ year lifespans and touch every aspect of the business are incredibly scary to touch.
So, at some degree of distance, the internets get. the definition mostly correct, but the reason it has chosen (eg all enterprise developers are stupid) is as simplistic as every other conclusion the internets have come to. While there are many people writing code in IT dev shops who really should be analysts, there are also a lot of smart people working in environments constrained like nothing your average startup developer has ever seen.
I've been there, and the only way I'm going back is if it's the only way to keep a roof on my kids' heads. I'll go homeless myself first! :)