Developing the ability to sneak through the surface on a start can help you carry more speed into your swimming.
While there’s no avoiding carrying air into the pool during a start, the more air you drag into the water with you, the more disruptive that start was. The bigger the splash above the surface, the more speed you scrubbed off on that entry.
Just like great divers spearing through the water with a RIPPED entry, swimmers can carry more speed into the pool by diving through a smaller hole. The goal being that the sooner you escape from the air you’ve dragged into the pool, the sooner you’ll have a surface to press on for your dolphin kicks.
The angle of your entry can impact this, as can the ability to hit the water IN streamline.
These are simply illustrations of swimmers landing correctly, and incorrectly. The most important part about what they’re doing is… practicing starts with focus to make them better, and seeking feedback not only from the feel of slipping through the water, but by checking their breakout points, and speed.
The goal should be… drag down as little air as possible, and escape from that air as soon as you can.