There are two sides --- as Abigail-II mentions, incorrect responses
require additional resources for correction and run the risk of the
answer being used before it is corrected. That, of course, applies to
all incorrect --- or suboptimal --- responses, not just those posted
be relative newcomers.
On the other hand, as moxliukas and Molt mention, many times an
incorrect or suboptimal response will generate corrective followups
that are more generally instructive to more people in the long run
than a simple correct answer alone would have been.
Personally, I fall into the second camp. That doesn't mean I support
total guesswork, or posting things that haven't been at least
minimally tested --- but I do not think 100% certainty should be a
requirement for answering. About the only thing I am 100% certain of
is my own fallibility.