Those are good questions.
Technically, it is possible for a cracker-style dough to overferment. However, because of the relatively low hydration of cracker-style doughs compared with other types of dough, the rate and extent of fermentation is much lower. By way of example, in the case of DKM's cracker-style dough, the hydration is 36%; for other cracker-style doughs, the hydration is not a great deal more, usually in the mid-40's or thereabouts. Most other types of doughs (but excluding deep-dish doughs) tend to have hydrations above 55% and, in many cases, considerably higher than that. So, even with a fair amount of yeast (1.2%) in DKM's cracker-style dough recipe, the rate and extent of fermentation is not excessive, and certainly much less under the same conditions than a dough with, say, a hydration of 63%. You could never get a dough with 63% hydration and 1.2% yeast to last 24 hours at room temperature. It would blow long before that.
Another point to keep in mind is that the yeast is used for somewhat different purposes in a cracker-style dough. In most doughs, the yeast is used to generate gases and to develop the byproducts of fermentation that ultimately contribute to to the flavor and aroma and other attributes of the finished crust. Gas production is not a big factor with cracker-style doughs since the doughs end up being crushed by being rolled out at some point, using either a sheeter/roller in a commercial setting or a rolling pin or possibly a pasta maker in a home setting. With cracker-style doughs, you get flavor contributions from two places: the yeast itself, because of its large quantity, and also from the byproducts of fermentation. For most pizza doughs with normal yeast levels, there is less flavor contribution from the yeast itself.
There are some additional differences between cracker-style doughs and other doughs as far as overfermentation is concerned. When most dough overferment, they become wet and slack and become almost impossible to shape and stretch out by hand without rips and tears forming. To the extent that the doughs can be shaped and stretched into usable skins, they are likely to bake up overly crispy, and even cracker like, and have poor crust coloration because of the depletion of the sugar--both the natural sugars extracted from the starch in the flour by enzyme performance and any sugar added to the dough formulation itself. With a cracker-style dough, the workability of the dough is less an issue, at least in a home setting, because of the use of the rolling equipment as mentioned above. About the worse that is likely to happen with an overfermented cracker-type dough is that the finished crust may lack color because of the sugar depletion. The desirable flavors contributed by the byproducts of fermentation should still be there. This is an observation I commented on at Reply 32 at http://www.pizzamaking.com/forum/index.php/topic,5762.msg49257.html#msg49257
. I should forewarn you, however, that the taste element can get out of control, as I noted in an experiment I conducted and reported at Reply 97 at http://www.pizzamaking.com/forum/index.php/topic,5762.msg50088.html#msg50088