[skarayan]

In my opinion, a reason for concern is different than believing their product is inferior.

At the end of the day, this is business. In business, there are many ways to battle the competition.

G+ is clearly gaining some initial traction and Facebook doesn't want their platform to be used to better the competition.

[law]

I think it's more nuanced than that. Facebook's reputation and brand equity is perhaps their second most cherished asset (second to their user base). A move like blocking Google advertisements will result in even more bad press when they really need to focus on delivering a better product.

In the end, however, I think Facebook will become obsolete. It's a technology like any other, and I think it has become too big for it to be everything to everyone. Of course, that's just my opinion, and I could be wrong.