The behavior of other participants is itself a first-class signal.

Rule 611 compresses that signal. By forcing everything to orbit a size-agnostic NBBO, it collapses a lot of the “behavioral bandwidth” (depth, imbalance, sweep patterns, replenishment, cancel/replace cadence) into a single top-of-book tick. Less resolution, less information.

High-resolution flow tells you who wants what, at what size, and how urgently. When we gate execution through protected quotes, we encourage tactics that flick the top-of-book with tiny size and discourage truthful size revelation. That’s signal destruction dressed up as protection.

Letting informed counterparties print away from the protected price (to reflect size or information) increases informational content. You get cleaner read-through from actual willingness to trade, instead of a compliance-driven dance around a fragile benchmark.

So yes: other people’s actions are the best data feed. The more of that behavior we can see—in size, time, and venue—the better our discovery gets. 611 reduces that visibility by design.