https://lists.w3.org/Archives/Public/public-vocabs/2015Apr/0059.html

why is the domain of http://schema.org/numberOfEmployees set to
schema:BusinessAudience? Shouldn't it be schema:Organization instead?

Although https://lists.w3.org/Archives/Public/public-vocabs/2015Apr/0060.html points out, some organizations might not have employees (e.g. a Residents' Association, or Anarchists Society, or many kinds of club), there are many kinds of organization for which an employee count is relevant.

Regarding Scope, let's keep this fix simple. Context: It is also worth noting that some organizations have important relationships other than employment, and that schema.org does not enumerate all such relations. For example, the students or alumni of a University are not employees. Similarly with companies and their owners, customers and contractors. If we were to attempt a general approach to counting, we would need to include time as a parameter (and probably model with Role). There are also some discussions around other count-related properties, which like numberOfEmployees are hardcoded for a particular measure at a particular time (e.g. see offerCount, ratingCount, upvoteCount, downvoteCount, answerCount, UserPlays, screenCount, answerCount, wordCount, reviewCount). The point of this paragraph is to argue that a simple fix is the best action at this point.

Proposal:

• Add: numberOfEmployees domainIncludes Organization

This is worth doing immediately, without delaying for any broader discussion of other relationship types (e.g. http://schema.org/member), time-indexing, etc. Note that there has also been some discussion about a generalized model for measurement, motivated by modeling concerns around sport, where many different kinds of thing are counted obsessively. See https://www.w3.org/wiki/WebSchemas/Measurement