Certainly, it just can take more time to sift through the list of tens of domains and deciding to allow or ban each connection if you don't already know which connections tend to be needed and which are not.

Still, it's perfectly doable for anyone if you experiment a little, and it's done once per site, so the time needed for this shouldn't be an issue. It's just that people working with this stuff will have an easier time using uMatrix - which is what I really meant in my comment above :)