He means specificly that saurus are bad without a very significant point investment. Anything less than a unit of 30 at 300 points is basicly useless, which is quite steep for a battleline unit to be usefull, and even that is still quite bad.
I’m essence you need to pour in a huge amount of points for them to be effective. While this can be devastating on the battlefield, it still is a point sink. The following issue is then a lack of flexibility if your warriors fail. At high point games they are very viable, but at lower points just go for skinks.