Boutique publishers make niche games for underserved audiences.What's a boutique publisher? First time I hear this expression. :/
I don't recall many IPs/proterties that WB owns that would be well suited for IO experience.
It's a way some mid-tier publishers try to stand out.
Hitman isn't a series that's going to sell 4-5+ million copies an entry in all likelihood, so it's seen as a niche audience title on the modern Western AAA scale.