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! :)