Even as someone who swam through high school, I often find that kick sets/drills give me the chance to isolate what I’m paying attention to (feeling my kick, when it feels good, and what I’m getting out of it).
For new swimmers, especially, it often feels like you’re trying to do 10 different drills and form improvements on every stroke. “High elbow… early vertical forearm… roll… don’t roll too much… reach… not too much… keep arms wide… but not too wide…. kick beats… not too much knee bend… toes pointed… head down… breathing to side without lifting…”
Focusing on one part of your swimming at a time really lets you quiet the voices and pay attention to the thing you’re working on. For me, it’s the same deal with using a pull buoy. I don’t need it to stay streamlined in the water, but using it lets me slow things down and completely focus on my stroke.