Probably overstated, and I say this as a man who loves tanks and makes his living from them.

The problem is that tanks generally had absolutely no operational capability whatsoever. They were just too danged unreliable. A significant portion of the few tanks which showed up in the first use at Flers Courcelette didn't even see the enemy, they broke down first. When they finally showed up at the battle of Cambrai in numbers, the overall battle was not an overwhelming success due to the lack of exploitation of the breach. Even after the Whippet fast tanks showed up, to conduct an exploitation resulting from a breach by the "Mark" heavies, they still were ridiculously unreliable. "Musical Box" gained fame by marauding away in the enemy's rear, but the fame for that one tank came because it was the only one to both make it that far and keep going.

I do not in any way wish to understate the tactical effect, they did perform sterling service in breaching lines (even if they were actually reasonably easy to knock out: a half inch of armour is only a half inch, after all), but what really wins is making proper use of the breaks in the line. In this, tanks were not particularly significant, and other techniques could be used to make the breach in the first place.

Of course, everything has to start somewhere, and I'd rather that tanks had shown up in the war than not!