Well, I can see Disney corporate offering hotel discounts to lure people back to Disney+, even if hotels and parks are packed. I haven't looked at the financials in a while, but the parks (to include the hotels) aren't the biggest profit maker for Disney as a whole. I could've sworn ESPN actually pulled in more.
But regardless, a small cut in hotel profits (even if they're full), to keep their Disney+ membership numbers high is probably worth it, since pay TV is only growing more competitive as cable loses it's grab on channel bundling.