You do? Even if that were remotely disputable, and it’s not, there’s one very famous example in Patriots lore from the last decade which proves that statement wrong.
Nobody will argue that, but that depends upon the secondary. Not the LBs. For example, the safety and corner positions in 2011 were trash. The team employed a ton of Cover-2 Zone, Cover-3, and Cover-4 in obvious passing situations. In 2012, after the Talib addition, the team was playing mostly Cover-2 with the corners in press man, but the LBs were still in zone. As a matter of fact, unless you’re talking about pure Cover-0 or Cover-1, the LBs are in zone the majority of the time in passing situations.