In my opinion, gantt chart have been an out-of-date tool and only available for some controlling management process such as factories or manufacturers. Because they relatively have sufficient data to make predictions about future.

However, in agile environments, we always face variable factors that cannot be reflected on a gantt chart and instead need collaboration, communication and innovation to assure cohesive to the product roadmap. I prefer lead time or story points to realistically estimate the system delivery capabilities that could provide real statistics.