Yeah they were frustratingly bad systems. I was a huge bo3 fan and it made me really sad that I couldn't use any of the cool new guns because I had bad luck on the slot machines :(
IMO Advanced warfare was worse because it locked some guns behind the crates, and also locked a ton of "variants" behind crates that were objectively better than the base gun
https://einstein-schrodinger.com/mercury_colony.html