Yes, the majority of agile teams are geographically distributed in some way. The 2014 Software Development at Scale Survey found that 39% of teams are (mostly) co-located, 23% of teams were near-located, and 38% of teams were far located as you can see in Figure 1. Please note that this survey only asked about development team members, not whether stakeholders were also in the room. Previous surveys have found that it is rather rare for stakeholders to also be co-located with the development team, the implication being that 39% is a very optimistic estimate for how co-located agile teams are.
As you can see in Figure 2, the 2012 Agility at Scale survey found that organizations are having success (the green bars) at all levels of geographic distribution. It also indicates that some organizations are failing (the red bars) at each level of geographic distribution. The implication of this study is that although it is possible to succeed with agile development regardless of how geographically distributed the team is, that there are not guarantees that you will in fact be successful. This is why the advice in this article should be of interest to you.
The bottom line is that some organizations have been very successful applying agile techniques on geographically distributed teams. In fact, as you saw in Figure 1 geographically distributed agile development is far more common than mainstream agile discussions seem to let on.