I read through all of it and actually understand what you're saying.
Basically you're saying that drones are used to make spines and spores, but other races have defenses for both air AND ground without having to do permanent economic damage to themselves. While this is true, if you look at that in isolation it looks imbalanced, but its much more balanced than you'd think due to the other mechanics of zerg.
Zerg can create a lot more workers than the other races with a lot more safety. Because of this, not only do you usually have the extra money you could be using on static defences, but you also can sacrifice some of your economy towards defences without it having a noticeable impact on your economy in the long run.
Another thing you don't take into consideration is how cost-effective spines and spores are. Eight zerglings take up 200 minerals and 4 larvae, two spines take up 300 minerals and 2 larvae. Test out the maximum amount of marines each can kill and you'll see that spines are actually more cost-effective than other possible earlygame defences. Spores are pretty essential to hold some timings themselves, and are yet again really cost effective when used correctly. I dont see how either is really underpowered.
In short, I think you're looking at it the wrong way, or just looking at a small part of zerg mechanics in isolation.
I don't personally feel like I'm wrong though in an educated sense... as you can tell, my approach to zerg would almost make them "seem" similar to terran and protoss but people do not want that.
I want you to look at it this way though coming from the philospohy of Hegel in generating 3 unique bodies.
Thesis + Anti-Thesis = Synthesis.
By having the spine and spore crawler produce linearly from the spawning pool as I said.. it shows a synthesis between protoss and terran.
For example, a pylon has a build radius for cannon, while the spawning pool would have creep (Build radius) for spine/spore.
The pool would produce defense in a linear fashion but have the upgrade for 2 slots.
Marines which are technically defensive produce linearly from the barracks, (They fill bunkers)
So you can see the synthesis there which creates an entirely unique because of the synthesis and inversion yet BALANCED because of the symmetry.
When you say that zerg can "Mass" drones... yes, but you have to remember that t and p are building offense when you're doing this... and B. zerg also shares production with the overlord.
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