Yes, Harry Kane is our main striker, but against the top sides, it can't all be down to him scoring goals. Sometimes he might end up occupying the defence, which creates space for others.
Kane almost always has 2 defenders on him at all times. This is why the Kane-Alli partnership works so well, especially when you have players out wide occupying the full backs. It forces the opposition to make a choice. 2 on Kane, means Alli will have the space, or 1 on Kane & 1 on Alli, means that Kane is more likely to find joy.