My practice is to adjust finished dough temperature based on the type of dough I plan to make and the fermentation method I plan to use. For example, if I want to make a typical cold fermented dough, such as a NY style or an American style dough, I try to adjust the water temperature to give me a finished dough temperature of between 75-80 degrees F. The range recommended for finished dough temperature for professionals is 80-85 degrees F (see, for example, Tom Lehmann's instructions given in Reply 3 at http://www.pizzamaking.com/forum/index.php/topic,7953.msg68396/topicseen.html#msg68396
). The reason for the difference is that commercial coolers are more efficient for cooling than home refrigerators (they run several degrees cooler than a typical home refrigerator). If I want to make an emergency dough that is to be used within a few hours, I will use a water temperature that can be around 120 degrees F.
The range of water temperatures I use can be very wide. For example, if I want to make a cold fermented dough that will last a few weeks in the refrigerator, I would use a water temperature of in the 40s degrees F. See, for example, Reply 29 at http://www.pizzamaking.com/forum/index.php/topic,3985.msg36081.html#msg36081
where I used water at 44.1 degrees F to make a dough that was cold fermented for about 12 days. I once even conducted an experiment in which all of the formula water was in the form of ice cubes, and another member, Les, perfected a method in which all or nearly all of his formula water was in the form of crushed ice. I have also tried using frozen and refrigerated flour to try to achieve a lower finished dough temperature. Using refrigerated flour is a method that Bev Collins, who worked for years in the R&D group at Domino's, often recommended (see, for example, Reply 26 at http://www.pizzamaking.com/forum/index.php/topic,4625.msg40011/topicseen.html#msg40011
). (I think I can find the links on these methods if you are interested.)
On the other end of the spectrum, if I want to make a dough that can be used within, say, an hour, I would use a water temperature of close to 120 degrees F and maybe closer to 130 degrees F. See, for example, Reply 12 at http://www.pizzamaking.com/forum/index.php/topic,2250.msg19793/topicseen.html#msg19793
where I used water at about 115-120 degrees F to make a dough that was used to make the pizza within an hour total, from beginning to end.
Professionals generally adjust water temperature for their cold fermented doughs. There are even charts that they can use that tell their workers what water temperature to use based on their particular mixers (and, specifically, their friction factors) and temperature conditions. You can see an abbreviated version of such a chart on the last page of the General Mills piece at http://www.gmflour.com/gmflour/PDFs/Website%20A49104%20Just%20Crust%20Brochure.pdf.
Absent such a chart, there are formulas for calculating water temperature to use to achieve a desired finished dough temperature based on flour temperature, room temperature, and mixer friction factor. Tom Lehmann discusses these formulas in an article at http://www.pmq.com/mag/2003spring/tom_lehmann.shtml.
I hasten to add, however, that the methods described by Tom work best for straight doughs in a commercial setting, as I discussed at Reply 18 at http://www.pizzamaking.com/forum/index.php/topic,10152.msg88757/topicseen.html#msg88757.
Since most of my doughs are straight cold fermented doughs, I find the water temperature calculations useful in even a home setting and use them pretty much for all of my straight cold-fermented doughs.
I tend to agree with Bill/SFNM that your acquaintance was perhaps thinking of doughs other than pizza dough. However, the notion of keeping things cold does have merit although I did not find that using cold yeast and cold flour (even frozen) had a lot of value in my dough making, at least for the quantities of dough that I make. I have found that both yeast and cold flour can approach room temperature quite quickly. That is especially true where I am in Texas in the summer. In my setting, if I don't use water cold enough, I run the risk of my dough fermenting faster than I would like.
As you can see, water temperature is not just an abstract notion.
EDIT (1/25/13): Since the link to the above Lehmann article is no longer operative, see the Wayback Machine link to the same article at http://web.archive.org/web/20070502014430/http://www.pmq.com/mag/2003spring/tom_lehmann.shtml
EDIT 2 (3/22/13): EDIT (2/4/2013): For an updated link to the General Mills brochure, see http://www.professionalbakingsolutions.com/water-temperature-chart
. The chart is at http://www.generalmillscf.com/~/media/Files/Industry-Resources/Bakery/technical-support/water-temperature-chart.ashx