That is true to some extent, but at the same time 10 man has harder qualities as well.
Case in point would be deaths. If 1 person dies in 10 man, that is 20% of your dps, or 33% of your heals and is not as easily recovered from. Same as 1 or 2 underperforming raiders.
In 25 man these kinds of deficiencies can be made up for. You are still easily able to kill a boss with 1 or 2 deaths, or underperforming people.
As a result I feel 10 mans require much a much more refined team.
That's not the logistic problem he is talking about though. It is that much easier to get a more refined 10 man team than a 25 man team that has some underperforming members. 25 man guilds are falling apart.