@ClintACK
Interesting theory - I actually posted a WAG a while ago that had a different take on 3eye. Here’s how I see it:
The Outsiders want in, however the various supernatural powers of our world have made a series of agreements (Unseelie Accords) to stabilize it & prevent infighting that would be detrimental to the fight against Outsiders. When Winter is strong it is able to guard the Gates effectively, preventing Outsiders from getting in.
As a result the Outsiders are forced to smuggle in a spy inside whose goal is to destabilize the Unseelie Accords, causing enough chaos for Winter to be distracted long enough so that the Outsiders are able to breach the Gates. Several books show a change in leadership hierarchy amongst various Signatories (White Court, Red Court, Winter Court, Summer Court, White Council, Denarians), where Nemesis is attempts to insert its own agents into positions of power but (seemingly?) fails.
On a different note, Harry notes quite a few times how much the supernatural world wants to avoid the attention of ordinary people. As JB points out, no supernatural creature wants to face an army of 20,000 villagers with pitchforks (now we have nukes), especially with a random wizard or KotC as part of the mix.
3eye is therefore an attempt by Nemesis to destabilize the mortal world. If ordinary people are able to perceive the supernatural & shown how much of a disadvantage they are really at, it would make them want to exterminate that which they hadn’t been able to notice before. Not to mention the drug’s addictive properties, which would allow Nemesis to control vast swaths of mundane folks in addition to its other forays into the seats of powers at other supernatural courts. This would destabilize the world enough for Winter to lose the war at the Gates.
@Snark Knight
I took the snatching of minor talents to be even more sinister. If the talents are minor without chance of improvement, they are devoured/ used by Fomor for bodies. If the minor talents can be enhanced further, they are used to call in the Outsiders we see coming up every now & then.