So, here's the basic gist.
It's ok for a Ship Class to have Strengths and Weaknesses. Battleships are Capital Ships are are considered "weak" against Destroyers, both for spotting reasons and torpedo threat mainly
Carriers are also Capital Ships and were powerful at dealing with All Threat Types. Not ALL THREATS, but Types. Enemies that were grouped with overlapping AA can be extremely expensive in terms of Plane Resources used when striking for instance.
As for Destroyers, the Broadside Reticle Rework mostly fixed the problem. HOWEVER, newer and less experienced DD players still weren't getting the message as to how Rockets work, so the Machine Gun animation does two functions at once:
a) It provides the attacked player with an indication of what to expect (the firing pattern is broadside)
b) It provides the attacked player with a small window of time to make a last minute movement/adjustment.
In addition to those things, it makes the Rocket Attack need to start from outside of the DD's Aerial Detection range (in many cases), which means a DD with AA turned off is a Very hard target to a CV player.
This is why the video I linked says the answer to the Best Weapon Against DDs... is Teammates.
You can strike DDs while your teammates Detect them. This allows you to line up shots.
You can detect DDs for your teammates to shoot them. This all them to line up shots.
The older system could reliably see DDs chiseled down and killed by a CV, which was able to do this in any non-AA burdened situation. Ultimately, pressure had to be pulled off the DD class and so it was.
Currently, your best defense in a CV against Destroyers is the same as against Submarines. Teammates.