The gospel alone does not lead to good works in a believers life – This is both true and not true.
If all one preached was good news and never gave any of the instructions of the Bible, or if one ignored the instructions or the law of scripture, one may find themselves unable to know what to do or what one should do with the good news. So, in that regard it is absolutely true. Having said that though, if one preaches a gospel that is mixed with commands, law, instructions and things to do, one may find themselves unable to appreciate the gospel or really know the demands of the law.
Only a message that retains the purity of the gospel is enough to give one the motivation, purpose and reason to produce good works. It is utterly impossible to be given a message that describes one as having moved from death to life and been given the riches of God’s grace at Christ’s expense and it not produce a result of some sort. That would be like someone saying that they had just been given the cure for cancer at the last minute, right before they died and it not producing a result beyond “OK, I’m cured”