Nicolas, well, HappyChic's post could refer to:

1. partnership with Mr & Mrs Smith, where
a) for some time properties not bookable as not integrated into GRS (Global Reservation System)
b) then integrated into GRS but several properties (in late 2022) not available all through to 2024 via monthly calendar showing all dates grey-ed out
c) perhaps some limited number of rooms allocated/available to IHG ....in searching Booking[dot]com such properties and/or unique rooms within a property were available

2. Bad value in using points at IberoStar.
Take a look at Mexico and Caribbean properties ... some IberoStars have price lower but points higher as compared to some IC & Kimpton
It could be that the bad points value is worse where few or no other IHG properties, but consumers/members who look at properties in a broad region (eg both Mexico and Caribbean) and see the relative good & bad value, and choose destination with better value.

Where IHG has no pre-existing properties on some island (or not within some large km distance), then possibly would stay at IberoStar.