Not necessarily. With an improved and higer age, one can fend off an attack from an invader if he has better troops. A smaller number of experienced, better trained soldiers will be a good deterrent from a larger, more unskilled attacking force.
Btw, the wealth income bonus is only proportional to its metal rate. You better have a lot of mountains if you want that huge wealth bonus. knowledge for the Greeks isn't proportionaal to anything else, it is self-generative of itself as a single entity.
The only way to get more wealth is through more cities (or temple upgrages, which in the beggining ages is rather inefficent and negligible), all of which cost hefty wood and food. So, spending most of your time searching for mountains and sqandering lots of needed food and wood to attempt to invoke a bonus does not seem as good of an advantage than the Greek knowledge bonus which actually uses the knowldege to ain library research against the opponent.
Library research, along with peripheral research, will Outpace another non-greek opponent. Heck, you can max out technologies to get a better military too (not that i wanted to).
The reason i am good at matches is that i have more technology than the other opponent(s). It is how i am able to fend off, attack then succesfully even without the best military/score/economy/what have you. Technology is the key to a better civilization
Pimp approved, master class!