Yes everyone knows about What3Words. It was an attempt to come up with an easy way to assign addresses for places where there are none. In the end, a proprietary addressing system will never gain traction, and of course the inevitable eventually happened. My personal feeling is that What3Words never really got us beyond x/y numbering and the logic behind an addressing system was not there. Enter Plus codes which comes at this problem from a different perspective. There is a very detailed analysis of existing methods and why they choose to go this direction that I'll leave it up to you to read.
Probably the biggest reason to pay attention is that this open addressing system was developed by Google. In fact, they are already implementing it in India as we speak which goes a very long way to making this happen.
All these systems are built on the idea the world is a grid, and how deeply you drill down into that grid is your address so things need not be a single point, they can be an area which opens up many exciting ideas for addressing, especially outside of North America and Europe. Check out the Github project to learn more.