Dev tools are not for 99% of end users and not realistically available to them (even if they stumble across dev tools, they don't know what they've found or how to use them). PDF editing is for end users and is realistically available.
That seems like all the more reason it's worthwhile. If they're going to invest in the tools for 1% of their users, why wouldn't they invest in tools for 50% of their users?