Of course, anyone can make a mistake, but people who research families rather than focusing on their direct line are going to make fewer errors on their direct line. Whether experience is a factor depends on what you mean by experience. Someone can have been researching their family tree for decades without acquiring much experience - experience isn't about time served, it's about learning from mistakes, learning from others, learning from doing, and learning by experimenting.
If anything it's the people who have been researching the longest who are most likely to have bad habits, or (to put it more kindly) habits they acquired in the pre-Internet days when many things took a hundred times longer than they do today, and some things were virtually impossible.
Fortunately I read
a good book when I started - so, even though I began my research at the tail-end of the dark ages, I developed good (though not perfect) habits and sound strategies.
Maybe the equivalent today is those who primarily rely on online indexes and other people's online trees without ever checking things out properly for themselves?
That's a different problem. Both involve a lack of attention to detail, but people who depend heavily on other peoples' trees are rarely one-dimensional in their approach, and it's rare for me to come across a LostCousins member who relies on other peoples' trees, for the simple reason that those sort of people rarely join LostCousins (or if they do, they don't participate).
By contrast, there are far too many LostCousins members who are one-dimensional in their approach - otherwise I wouldn't have written that article. Indeed there are some who are only researching one or two of their family lines, and are only interested in finding living cousins who bear one of those two surnames (and amazingly, some of those researchers are women - so much for equality).