Thai painters" or the Dutch or Thai categories. The first two know only about one painter who is Thai. The Thai Wikipedia knows about 24 painters.
At this time Wikidata knows about 20 Thai painters. It takes a little effort to add any missing painters known to a Wikipedia.
When all the Thai painters known to Wikipedia are known to Wikidata, it means that its quality to list them is as good as any Wikipedia category. Obviously there are many more notable Thai painters. They all deserve to be known in Wikidata.
Reasonator is able to express the quality of Wikidata. It uses queries that are based on the Wikidata data. By quantifying for example the painters from a given country, it becomes obvious what Wikidata has to offer. Reasonator can do a better job than any category that can be expressed as a list or a query.