Specialization mostly a problem in monocultures.
If you almost only plant wheat, you are going to end up with one hell of a pest problem.
If you almost only have Windows XP, you are going to have one hell of a virus problem.
If you almost only have SearchRank-style search engines (or just the one), you are going to have one hell of a content spam problem.
Even though they have some pretty dodgy incentives, I don't think google suffers quality problems because they are evil, I think ultimately they suffer because they're so dominant. Whatever they do, the spammers adapt almost instantly.
A diverse ecosystem on the other hand limits the viability of specialization by its very nature. If one actor is attacked, it shrinks and that reduces the opportunity for attacking it.