When you need to open a specific file, program or service on Windows you have multiple options to do so. You can use the taskbar or start menu for that, browse a hard drive using a file explorer, or search to find the item of interest.
Windows Search has been integrated into the operating system for a long time and while it does a good job at finding popular services and programs, it is not the best nor the fastest when it comes to anything else.
Desktop search tools offer faster searches, better options and filters, and a better user experience as a consequence.