As someone who has both hosted and participated in the majority of the trade-offs here, I think that's a bit of an overstatement. There definitely is an issue with certain users not submitting reviews, but I'd argue that those users exist within an extreme minority and are the exception, not the norm. The majority of participants usually do submit their reviews, even if they're late. For the small percentage of users that don't follow through, we've enacted a blacklist (though I admit that we need to be stricter about enforcing that).
Using the current anime trade-off as an example is not a good idea. I specifically altered the rules for this trade-off, making things much more involved than they usually are. So I went into this expecting that many users would not make the deadlines. And it's ok if they're late, as long as they follow through within a reasonable time frame. Furthermore, you can't use the dates like that either because there are specific variables that have not been taken into account. For instance, the review deadline was the 25th, but the deadline for sending out mixes was on the 18th - which is only one week apart. Some users did not send out their mixes until after the 18th, so the members that received their mix late had even less than a week to write their review (if they wanted to fulfill the technical deadline). So when you take those factors into account, you realize that no one has had a month to write their review, because they haven't even had their mix that long.
Indeed, life is busy for most of us, so we do try to give a bit of leeway with these things. Because at the end of the day, this is just for fun - it shouldn't be a chore. However, you are absolutely correct to say that people should know what to expect when they sign up for these trade-offs. If you can't fulfill the commitments, then don't sign up.