That's just vile. is there any /good/ defense of this kind of agreement other than a 'think of the children' argument that people might make a mistake in their performance reviews?
That article only lists MS and Oracle though. Apart from IBM, I don't think CockroachDB Enterprise has such a prohibition, nor does Google Spanner (I think?), nor does Amazon Aurora (again I think?). And of course all the open source competitors don't have this clause.
Basically my impression is that DeWitt clauses are common enough to be well-known, but still in the distinct minority. That's just an impression though.