Saying they "picked him" is not entirely fair. It wasn't a litter of puppies, there are two sides to this story, as well as their shopping needs. Alcantara was not traded we have no idea why he hasn't been other than he still hasn't been. Sonny Gray wasn't a controlled starter; the last thing this team needed was another SP who's hitting FA next year. Same goes for Peralta. Also do we think the Brewers and Cardinals were realistically dealing those guys to the Cubs? Kyle Harrison was a failed prospect up until that point; be real and understand the team wasn't going into the 2026 season banking horsefeathers on him. It's cool for the Brewers (I guess) that he's found himself again, but the Cubs were not in a situation where they could throw-spaghetti at the wall with their rotation. They needed someone who had some MLB success. The Brewers were in a more stable pitching situation and could take that leap.
They didn't deserve to be criticized for the move. They didn't then; Cabrera was coming off a very successful season, at the age of-27, and was controlled for years. The price was pretty on par with that. There was risk involved, as there is any time, but that was reflected in the price. They don't today; Caissie has been bad, too. We can use hindsight all we want and say "they should have traded for Kyle Harrison" but entering the year he had been objectively bad no one gets the benefit of hindsight here.
Most of the objections to Cabrera revolved around his injury status. So far, that's been fine (at least on things people we worried about. Hamstring/adducter issues were not in his history; that was an accident). His issue seems to be that he's really struggled getting lefties out this year and staying consistent.
If you want to find criticisms it may come in how they've worked with him and how he's taken to those changes. I think that's probably a fair critique. However, I don't think a victory lap of "I always knew this dude sucked" really makes much sense in that the quality wasn't really the issue at the time of the trade as much as the other things were.