Er... yes. It's called sampling and it underpins just about all research in the physical and social sciences.
You're actually not interpreting the abstract (summary) correctly: it does not state that 26 reported no problems, it states that 26 did not have a chronic
(i.e. long-term) skin disorder
. In fact, as the abstract states very clearly, two-thirds of the respondents reported some
skin problems - including sweating, erythema (inflammation) and blistering - when doing hot sugar work.
In this article, two doctors are trying to find a solution to painful skin problems that thousands of hot sugar workers experience; they think they've identified a preparation (cheap, and already available from pharmacists as a remedy for excessive bodily perspiration) that helps in some cases; they've tested it on a sample of participants; and have published their research in one of the world's most prestigious medical journals.
What's the problem?
Personally speaking, I think any
research that concentrates on the occupational health of kitchen workers should be encouraged and supported. I'm not clear why some of the responses to this thread are couched in such negative terms.
It did make me remember, though, the children's writer Alison Uttley
's description of a woman making pulled sugar sweets at a fair in England in the late 19th century: hanging the mass of melted sugar from a hook and greasing her hands thoroughly with spit before beginning to pull the sugar!