iTunes Match uploads any of your music that is not available on the iTunes Music Store. For example I have numerous classical albums that I converted from vinyl LPs that simply aren’t found anywhere anymore. I also purchased CDs from classical music sources that are, again, not available in the iTunes Music Store and most likely not available on Apple Music either. Some of us have non standard musical tastes, especially when it comes to classical music. The same could be true for older music by bands that have not released their work to online music stores.
If your entire music library consists of songs that are all available on Apple Music then yes, iTunes Match is probably redundant for you. If you have custom ripped music that you want to be available on all your devices then you will want to keep iTunes Match.