This is a small focus-group study that reports qualitative conclusions. It's not like they're trying to calculate statistical significance or something. It's aimed to be a better version of the "folk wisdom" that pops up on sites such as these.
Focus group studies have value. They're a kind of evidence that pushes weakly across a very broad front. Controlled studies are a scalpel: they produce high-confidence answers to very specific questions. Sometimes instead you need an axe. You don't know what specific question to ask, and sitting there doing controlled studies with no real clue about what's going on isn't going to be productive.
I'll put it this way: when you don't know much about a subject, there's an almost limitless number of hypotheses to consider. It doesn't make sense to prematurely promote one of those to the status of "working theory" and start doing properly controlled studies to test it. You have no real reason to believe it in the first place.
Focus group studies have value. They're a kind of evidence that pushes weakly across a very broad front. Controlled studies are a scalpel: they produce high-confidence answers to very specific questions. Sometimes instead you need an axe. You don't know what specific question to ask, and sitting there doing controlled studies with no real clue about what's going on isn't going to be productive.
I'll put it this way: when you don't know much about a subject, there's an almost limitless number of hypotheses to consider. It doesn't make sense to prematurely promote one of those to the status of "working theory" and start doing properly controlled studies to test it. You have no real reason to believe it in the first place.