That’s why these surveys are dangerous: they are tautologies. Adopting your words, if anyone disagrees with the premise, they cannot answer. Therefore, if 80% of participants are actually “-1” about the premise and have no choice but to close the tab or confirm something that is not their opinion, the results will still show: 100% are “+1” agree to the set premise.
False presumptions corrupt data: depending on the perspective, the data itself can be seen as corrupted, or the group on which this data applies. But the result is always the same. Yet, in Fedora surveys, false presumptions feel like a tradition.
Creating an expressive survey is not a trivial task, but it is in Fedora mostly treated that way (at least in most surveys I have seen), and then the data is used… despite the fact that it might reflect only the opinion of a small group, even if it says 100% +1 
Imho, this should be done by a SIG with the very expertise (if we can come up with that), or stop creating+distributing misleading data.