I have actually seen people worrying about the computational burden of handling all the extra data this could produce. I seem to recall someone actually doing back of envelope math and concluding that federation with threads would be cost prohibitive for a lot of instances.
If that is true then the whole debate we are having is irrelevant because federation will basically not be possible for websites which are seemingly being operated without anything resembling a business plan.
I always find screenshots from apps confusing. Also I don’t use IG. What is the context of these text boxes? Who is “promoting” the posts? It sounds like an ad from the user who posted it, but the accompanying text says it is advertising Threads.
I notice that the image posted here and the one in the comments by @wolfshadowheart have the same content but the usernames are different. Are they mirror accounts?