After the writing had been on the wall for years, Apple only recently officially stated that it won’t be producing Wi-Fi base stations anymore. Many of us have relied on the AirPort line as an easy way to handle a number of basic network tasks without learning the vagaries of other hardware. One of those is network file sharing.
You can share files from macOS or Windows, but it’s not always convenient or applicable, especially if you (or your family) relies largely on laptops. Another option is network-attached storage (NAS), which are standalone file servers that often come with a lot of additional features, and now start in the low hundreds of dollars for “bare” units without any internal drives.