Very, very unlikely, with how these things fail. There's a reason why joists and studs have the spacing they do. Also, when a joist like this fails, it doesn't fail completely with the floor suddenly dopping out, it'll crack, hang, the rest of the system will take the load, as designed.
Source: I've built and maintained a few houses, reconstructed these kinds of failures. Even in really old homes (early 20th century) with dried out lumber, a single joist completely failing (say, rotted out) only causes a low spot. The subfloor will sag, but not fail, as it's securely attached in multiple places to each joist (which is why a failed joist just hangs).
I can't even imagine a way for more than a sag to happen.
Not all dimensional lumber is completely dry, which is why it warps and potentially splits. There are three ratings: GRN for having an excess of 19% moisture at the time of surfacing, KILN or KD for no more than 19%, and MC15/KD15 which has no more than 15%.
This is not necessarily common knowledge either.
Anecdotally, I have bought soaking wet wood from Home Depot before. It sucked because by the time it was dry enough to use, every single board was as crooked as a politician looking to get reelected.
Yep, true. Lumber after COVID due to the ravenous home construction industry was substantively wetter. But it was more trustworthy than a piece of timber.
