Let me quote the important part, emphasis mine: "...majority of players, after trying both playlist types, chose to stick with Open Weapons...". So not only that the players they are talking about seen the Open and Close options, they even tried it and then decided to stick with Open. In other words, they are talking about players that tried both modes, not all players, so there is just a very little or no bias. I think their statement and reasoning is pretty clear.
Except if you wanted to complete the in game challenges you HAD TO PLAY OPEN.
The data was manipulated. We all know it was.
As I said in other post here - depends what exactly they measured, when, and how. I don't know their methodology and you don't know their methodology either. I assume that they know what they are doing and thus their statements are correct (as they must be aware that players will eat them alive for any inaccuracy). Any claims that "the data was manipulated" seems pretty unfair to me. But if it was manipulated - prove it beyond any doubts and then there can be made a discussion about it.
I don't recall that being a thing. The challenges were largely very simple and I myself did both versions and got progress in both. Maybe there was some weird bug for some folks but yeah no it definitely worked open or closed.
