Someone wrote their questions/answers wrong for the Lab: writes with failovers. It wouldn’t cause an error. Because 3 nodes, with 1 unhealthy is still 2 which is the majority. So you’d get a check for that.
Please check you messages for detailed explanation.
Let me know, if you have any doubts.
The question was right. The explanation/detailed answer made sense. What I had wrong was falsely assuming that an empty wtimeout had a default. Mea Culpa.