Redundant system pretty much means a system with built in redundancy (redundancy is not an inherently negative word) so that if one part fails the rest is still functioning. As in one of the 3 raxes explodes, but there's two more in the same area so it's ok.
I suspect that you don't realize that redundant has multiple meanings, two of which are used here. The first one is using the word redundant to mean useless multiples, in that there's no such thing as as pointless secondary or tertiary barracks placed near another barracks. The second one is using the word redundant to mean a backup in case the other one dies. You know, like in a redundant array of independent disks, or RAID for short.
Ditto for kidneys as well. Spartacus fails again. Someone actaully put "Freeball it" there? Hah. The description is balls though, CW just plain failed at all fronts one time, which prompted HSM to say that, noone just flat out refused to do what he said. But yeah, there should be a cleanup of that page. Ninja - The attempt of a player (especially Scout w/Hide upgrade) to sneak into the enemy base and destroy key structures (especially the CV) without the enemy noticing before it is too late. Who the f typed this one? That not at all what it means, Cv is not a structure and there is no mention of ninja raxing. Spawnnkill
I want to throw out there that it was Valiant (of CW at the time) that taught me you can never have enough spawns. He used to just place raxes all games without relenting, even way in our own territory when we were sieging their base. It pretty much makes it impossible for an enemy to retake an area without huge commitment from the enemy team, which, should you have a team coordinated enough, you should be able to counterpush and take quicker.
If given the choice, which do you drop, a rax or 2-3 turrets? I hate turrets and love dropping raxes instead. Or at least I prioritize extra spawns over extra turrets. I'm probably a worse com for it, but that's just how I've grown to com. TIL English is literally a wild turkey.
Turrents: can be killed by any class and unless you have lvl3's are easy as fuck to kill unless placed in very specific spots. Raxes: Shit out soldiers and take a significant effort to kill.
That's my argument. But it ultimately relies on your team being not-shit. That's not a reasonable assumption most of the time... ...which is why I often get lvl3s.
I feel like pointing out this also really depends on how many people are playing. I rather have a couple turrets instead of a rax right next to it/ near it if player count is low and/or my team is inexperienced.
I'd much prefer raxes, but like you, I know it's probably not the optimum decision. Turrets are certainly better at defending than the current playerbase we have which doesn't killspawn. On the other hand, with UGL currently very popular in the meta, that does counteract turrets somewhat. To put it simply, you're going to get fucked whichever decision you make. It's really case of what your team is capable of. Obviously playercount does make a difference - the fewer players, the better turrets are. But even so, the main difference is whether people will actually killspawn to defend the base. You can drop 5 spawns in one area you hold, but if people just refuse to killspawn to defend it, then you've just wasted resources. Obviously in a pug setting, this isn't an issue.