What's the point of naming grid lines?

<div class="wrapper">
  <div class="item1">Start column line 1, span 3 column tracks.</div>
  <div class="item2">
    Start column line 6, span 4 column tracks. 2 row tracks.
  </div>
  <div class="item3">Start row 2 column line 2, span 2 column tracks.</div>
  <div class="item4">
    Start at column line 3, span to the end of the grid (-1).
  </div>
</div>

.wrapper {
  display: grid;
  grid-template-columns: repeat(12, [col-start] 1fr);
  gap: 20px;
}

.item1 {
  grid-column: col-start / span 3;
}
.item2 {
  grid-column: col-start 6 / span 4;
  grid-row: 1 / 3;
}
.item3 {
  grid-column: col-start 2 / span 2;
  grid-row: 2;
}
.item4 {
  grid-column: col-start 3 / -1;
  grid-row: 3;
}