If sub-par effects are disqualifying, then most of these films are disqualified. Will you believe a man can fly? Not through watching the original Superman; those effects are totally janky by today's standards!
Bad special effects are certainly a disqualifying item in my book. However, I also don't only judge special effects by whether they are simply realistic or not. IMNSHO, whether the special effects are "good" or "bad" depends on a couple of factors.
- Do the effects properly convey the narrative that they are supposed to. Basic film making here, but important to consider.
- Do the aesthetics of the effects match the look and feel of the rest of the movie; are they visually consistent. Effects that are jarringly different from the style or feel of the film draw attention to the effects in a bad way. For movies that are supposed to be "realistic", this is where you want effects to look "realistic", but it's important to remember that "realistic" is a relative term. I don't care if effects look "old" as long as they look like the same age as the rest of the film, and match the rest of the cinematography.
- Probably the most personal - Do the effects convey the emotions that they are supposed to. Like blood in a horror movie: too little doesn't tell you anyone is hurt, too much is silly, but there's a "just enough" amount to convey the fear or grossness that is needed (and sometimes that amount may be different than what is realistic).
Consider RoboCop. ED-209 is literally janky. It's stop motion animation against live action. Of course some people will say that it doesn't "hold up" to modern effects. But to me, it's perfect. The motion matches perfectly with Peter Weller's Ivan-The-Terrible-style exaggerated movement. The aesthetic blends well, especialy with the other tech and in-universe media that we see in the film. The effects are obviously unrealistic and dated, but I still say they're great, fun, and highly effective.
Putting all that together, I have to say that I agree with
@OB1 any others that complain about Black Panther, because there really are some jarringly bad moments. It's not simply that the CGI looks bad, it's that it's blatantly a lower tier of special effects from other things we see in the MCU, which is a jarring aesthetic mismatch. The visuals are even inconsistent with other depections of the same characters in other parts of the same movie. To give credit where it's due, though, I will say that even the effect that are bad do a good job of conveying the fight; the blocking, action tracking, and mise-en-sen are still well done.
