Once you start to explore the data, the whole thing stops to be linear but gets to be very iterative, jumping over the wall every now and then. I.e., you may find out that the data cleaning is insufficient, or the model you have in mind needs some other transformation of the data, or you might want to collect additional or other data altogether.
The wall does exist, but I think it is more separating two kinds of people / thinking.
One thing is for sure: we won’t succeed if analysts continue to build useful but technically insufficient tools and computer scientists still build fancy tools that merely help the analysts.
Or even better: analyst and tool builder become the same person. That’ll take much longer though, so communication is a good place to start.