Can you elaborate why you think merging master into the feat branch keeps team velocity higher than rebasing the feat branch with the latest version of master?

Can you elaborate why you think merging master into the feat branch keeps team velocity higher than rebasing the feat branch with the latest version of master? With rebasing, it seems to me to be easier to maintain a clean history (no merge commits) since all merges end up being fast forward, with the added benefit that I can deal with any conflicts as and when they come up rather than fixing them all at once when I eventually merge to master.