The early/late debate's framework follows Broadbent's hierarchical perceptual processing model combined with communications-engineer assumptions about capacity limitations.
A reason why assumptions about linearity may have been problematic is that when, following Broadbent, we think about hierarchical perceptual processing while bearing in mind the communications engineer’s concerns about capacity limitations, it then becomes natural to make some additional assumptions about the way in which this hierarchically organized architecture supports personal-level cognition. The early/late debate’s problems are more plausibly blamed on these additional assumptions, rather