I'm pretty sure that is incorrect, (but I'm willing to be corrected if you can provide a link to some relevant information).
The uBlock and uMatrix documentation is not very good at explaining how they work together.
uBlock Origin and uMatrix are by the same author and are designed to (optionally) work together.
uMatrix does matrix-based filtering, and handles cross-site requests.
uBlock does pattern-based filtering, is a "wide-spectrum" blocker, which can function as an "ad blocker".
They have different, complimentary functions.
The confusion is probably because uBlock does have an advanced mode which allows dynamic filtering and is a little like a "uMatrix-lite", but I don't use advanced mode since I use the more powerful uMatrix.