The Issue: To protect their Intellectual Property (IP), DTL (like many prop shops) tends to compartment tasks.
The "Pit": You might get stuck working on a very specific, niche part of the trading pipeline (e.g., only data cleaning, or only execution algorithms) without seeing the "big picture" of the strategy.
Career Risk: This limits your exit opportunities. If you spend 3 years there but only know their proprietary internal tools and a small slice of the stack, you may find it difficult to pass interviews at other top firms that require end-to-end strategy knowledge.