The tendency toward overspecialization in the study of artifacts is unfortunate.
Conclusion
It's unfortunate how scholars studying artifacts tend to overspecialize nowadays (it'd be better if they had a broader range of expertise).
Evidence
Their understanding of whatever art period they're studying could be enhanced by studying earlier art that influenced it.
Evaluate
When we're trying to extract an implicit principle, we're sort of doing the upfront work of Parallel reasoning, except we wouldn't usually be diagramming anything, just trying to think of the general essence without referencing the specific topic.
The passage is saying that focusing too much on one thing can lead to a deficient understanding of it. You could potentially understand that thing better by also focusing on some of its influential precursors.
Goal
I'd probably be looking for something like,