I suspect the point is that people often say, in discussions about the GPL, that they expect commercial users of their BSD/MIT/etc licensed software to /usually/ contribute their changes back even though they're not obligated.
My anecdotal experience with this, having done many contracts providing commercial modifications of OSS, is that the companies that contribute their changes back is a tiny tip on the iceberg of use and modification.
That's not to say this is bad, if it's what one intends. But it's frustrating to watch people denigrate the GPL, sometimes, because of their wishful thinking about other licenses.
My anecdotal experience with this, having done many contracts providing commercial modifications of OSS, is that the companies that contribute their changes back is a tiny tip on the iceberg of use and modification.
That's not to say this is bad, if it's what one intends. But it's frustrating to watch people denigrate the GPL, sometimes, because of their wishful thinking about other licenses.