Not really, it isn't an offensive term inherently. It's just a lot easier to say than "the XXth% percentile of customers by spending" or "customers who spend Y% more than the median" or whatever else. The exact definition varies by organization. Identifying and attracting whales is a big part of a successful sales program.

The fact that an analogy is drawn to an animal may be dehumanizing in the most literal sense, but it does not seem offensive or carry a negative connotation on its own, as the term 'dehumanizing' implies. If it indeed dehumanizing as the term is actually defined, then what you're saying is that discussing the spending characteristics of a customer somehow deprives said customer of individuality (the definition of 'dehumanizing' in its non-literal sense, where it carries the negative connotation). But how else can you describe various cohorts of prospective customers except to describe traits like spending behaviors?

This just seems like overblown outrage and much ado about nothing, fanned by how fashionable it is to go after Facebook these days.

Exactly. Coupled with it's complement: "roach" or "cockroach" was similarly used in sales to refer to non-spending tire-kickers.

I bet you'd find a few more issues with children being called such because they only played the free tiers, or didn't take part in micro-transactions to get ahead.