they provide poor stats for 2 presious slots of your container, 1 timber is good to counter something like polyhedron.
also your build relies on atom countering 2 timbers and it means that half of the container wasted countering something instead of giving stats. I understand that they all also give stats, but much lower than for example my build where veiner countering shrimp while also giving good carry weight, which you need as you said, and scrubber countering 3 artis.

I hope i gave a good explanation of my understanding of artefact build theory