Blanket statements like that just aren't useful. The world is always a more complex and varied place than you believe it to be. That statement may well be true for the person who wrote it, but to try to apply it to everyone?
Many photographers work one-on-one with individuals (as an architectural photographer, my client may be a FIRM, but ultimately my repeat business is still driven by my direct relationships with individual architects within that firm. I'm Facebook "friends" with many of them. When I blog about a project, or update my portfolio album on Facebook, they all get the update, they all get reminded about me.
Not all marketing is designed to sell a widget, right away. The most effective marketing I've ever done was nothing more than building name recognition, over the very long term. Facebook is just another arm of that effort.
Faulty logic. Almost every TV viewer HATES commercials, but that doesn't stop TV Commercials from being very effective advertising.
Which neatly illustrates a point I made earlier about how large a role FB plays in different cultures. In the US and Canada I think it is welcomed far more as new channel of communication than it is on this side of the pond where it's generally perceived as a site for dizzy teenagers and gossipy housewives. 'Real men' tend to avoid it and around here the lads just pick up the mobile for a chat rather than bother going online, the bush telegraph still works just fine thank you. Society in the west of Ireland is incredibly closely knit under the surface and far older and more set in its ways than that of the new world, the UK may well be slightly more receptive to it as a business tool but not to any great extent and I really can't see architects and other professionals scrambling on board any time soon.