I think you're missing the point. Clicking a button that says "I don't want to see this movie" is exactly the type of criticism you give a movie before you see it.
But more importantly, if someone wants to criticize the way the film is marketed, or the opinions expressed by the artists that make it, I feel those criticisms should be heard. Personally, I like to get all of the information about something - both good and bad. I don't need big daddy rotten tomatoes to protect me from someone's opinion. I'm a smart guy, I can separate the wheat from the chaff.
As for "Facebook groups", If groups of like minded nerds want to use the power of their collective voice to espouse a collective nerdy thought, more power to them. In the case of Captain Marvels "Want to see this movie" score, I'm sure many pro-feminist "trolls" drove up the numbers as well.
What Captain Marvel is counting on is a huge opening weekend and making this an event movie. Marvel has a TON of nerd cred, so it's going to do phenomenally well. But so did The Last Jedi, which counted on Star Wars having TONS of nerd cred. The Last Jedi soured a lot of Star Wars fans.
By the time Endgame rolls around this will all be forgotten. I don't care if Marvel Studios tells me that Captain Marvel is going to swoop in like a Mary Sue and deliver a sonic kick to Thanos jewel sack to win the day...I'll still see the dang thing opening weekend.