I totally agree with your comment, the C2 of an air defense unit works exactly that way, but I also partially agree with
@Atomicfrog
For what reason partially?
Because for planning purposes, the actions related to the deployment of the anti-aircraft artillery control and warning system in support of a coordinated attack can be divided into three distinct phases, which will influence the the way the sensors will be positioned. In one of the three phases, the responsibility for detecting as far as possible in the direction of the enemy lies with the troop that is in contact and this advancing troop will not be covered by adequate sensors to perform this function, often using their hearing. In this way, the anti-aircraft artillery of the troop that is in a zone close to this advanced unit against the enemy will deploy its sensors in the direction related by the advancing units in order to provide radar coverage of their established anti-aircraft defenses, trying to coordinate with the other units that are deployed nearby, this radar coverage, if well targeted, may well employ only passive channels.
Let's say in a hypothetical example that the unit in contact with the enemy has not been able to carry out the reconnaissance of tactical aviation or enemy helicopters because of the absence of sensors and radars in addition to not having heard or seen the aircraft flying over their positions, this will inevitably give a shorter response time for air defense units that have these sensors because they will not know where to point and believe me, these radars and sensors do not operate 24/7.
This example clearly stands out in relation to land-based air defenses, while your C2 example of an air defense unit serves both naval and land commands. As he exemplified the case of anti-aircraft guns and MANPADS, this situation of using hearing in a C2 requirement of an anti-aircraft unit is still valid if we are going to analyze that this will only serve for units that are in contact with the enemy, sometimes elements of reconnaissance, special forces element among other elite forces capable of performing such communication and validation of air targets.