See , I understand your point.
You loved the movie and so did many in our forum but many also thought it was just ok. The thing is those section of "DC fans" can''t sabotage cinemascore. They just don't have resources to do so.
Also , RT verified score is very reliable. yes, it can get sabotage by usual suspect but chances are very low and at best fraction of reviews.
Captain Marvel was sabotaged on RT and Imdb and it has an cinemascore of A.