This is a pragmatic piece of Fowler on the rather dry topic of Object-relational mappings - in short, the attempt to marry an object-oriented code base with a relational data base.
Usually you’d get enough early success to commit deeply to the framework and only after a while did you realize you were in a quagmire - this is where I sympathize greatly with Ted Neward’s famous quote that object-relational mapping is the Vietnam of Computer Science
What Fowler refers to here, is Ted Neward’s article “The Vietnam Of Computer Science”
Does it, if you can work on the normal application code, there’s no reason you can’t work on the lower levels of applications. It’s all just code. Ramp up might take a bit more time, but I wouldn’t expect horrendously so. As long as your patterns make sense and what is there is written well enough and is not a spaghetti monster in the making, any one should be able to pick it up.