It seems like the main pitch here is auto-inclusion and auto-exclusion of various tools via an orchestration agent (which may or may not be the main model itself? Unclear from their post)

Mostly this seems like an end-run around tool calling scalability limits. Model performance degrades heavily if the field of possible tools gets too large, so you insert a component into the system that figures out what tools should be in-scope, and make only those available, to get reliability higher.

In terms of "why outsource this" it seems like the idea is that their orchestration agent would be better than a cruder task state machine that you would implement yourself. Time will tell if this assertion is true!