With the caveat that the stored events are not conflicting with each other. So a central instance needs to check each event for validity before allowing it into the log. The check cannot be parallelized easily without introducing races between event insertions.
No event sourcing architecture I know of advocates that at all.
One of the strengths of event sourcing is that you can fix things after the fact. Say you got a wrong event like you suggested that conflicts. You don't check it at the time before allowing it in log. You notice the wrong event, delete it, and replay the log.
You can always replay the log to get you current point of time.
