I think at a certain point a company reaches a size where there are functional units that generally do independent work and the founder has little to do with it

I think at a certain point a company reaches a size where there are functional units that generally do independent work and the founder has little to do with it -- if an investor has an interest in that area (or ideally experience/advice to offer) it makes sense for some members of the team to be involved in the dialog, though probably not the guy writing the algorithms in c++.