When we acquire, promote, or release the critical section, we must first take the database or collection lock in MODE_X for the target resource. Taking this lock drains any in-flight operations and guarantees that the current thread is the only one that can access the resource. Today we obtain the lock through AutoGetDb / AutoGetCollection.

Those RAII objects both

1. acquire the requested lock, and
2. return a reference to the database/collection, which triggers placement version checks.

For the critical section, step 2) is unnecessary—we only need Lock::DBLock or Lock::CollectionLock. Leaving the placement version check in place can lead to surprising failures.