But no company would simply give away free stays. That would cost them with no benefit.

There is a clear if unstated expectation that they will receive positive reviews and promotion as a result.

It will be marked as an expense outgoing to a third party by Disney, and the third party will be named or identified. That third party if did not account for that income and get audited, will be provided a demand letter. Vast majority of the "audits" are fully automated using cross referencing expenses & deductions to incomes.

There is no such thing as "free" when it comes to the US IRS.

None of this means that you have to pay taxes.

But yeah, you're right. If you get audited, you might have to explain to the IRS that this is not compensatory income.