The problem Red Shell is trying to solve is the "download divide" -- You can track clicks/users on the web before they download, and you can track them after they launch your product, but you can't easily connect the two.
As for why devs want this, if you know ad campaign 1 cost $1 and had 2000 clicks, and ad campaign 2 cost #1 had 1000 clicks, that is helpul but what you really want to know is "what is the lifetime value (LTV) vs cost of acquisition of users from campaign 1 vs 2" because if LTV is significantly different then despite higher cost it may clearly be worth it. But if you can't connect a user from before the download to after you can't do this sort of calculation.
Devs really don't care who the users are, we just want to know how effective a campaign is compared to one another.
Source: Was planning on integrating Red Shell ourselves before this (false) outrage made us cancel our plans.