I don't think IMDb realizes just how many
people read the boards without actually posting. Forget the main boards, this is the first time I ever even visited them. The real power of the site was in the title specific threads, where you can get a feel for a particular title before you watch it. Now IMDb is going to be just another movie catalog, albeit a big one, but a spayed and neutered version of its former self. They're making a huge mistake here and you can expect to see some form of message system back in place once they realize it. It might be a paid version or whatever, but I can guarantee you that trolls are not the reason why it's being shut down. That's just dumb, and they can give a crap less about trolling. It's all about money, one way or the other it's always about money. If they were losing traffic because of trolls, getting bad press in mainstream media because of it or if it cost them an inordinate amount of money, then I could see why they might shut them down. None of that is the case though.
The IMDb messaging system is archaic, simplistic and lacked any modern message board features, they even purged inactive threads at a crazy fast pace. It couldn't have cost them much, if anything to run these boards. Server space and bandwidth for these boards probably cost very little and would likely have brought in more revenue than it cost to run. There's another reason why these boards are shutting down and we'll find out sooner or later. But the one thing I can absolutely guarantee is that they'll realize they made a mistake at some point. It might not matter because the site is owned by Amazon and they can easily absorb any loss, but it will be a mistake nonetheless. Someone will create a forum linked to IMDb using their API to replace what was currently in place. That will piss them off even more and we'll at least get to see some fireworks.
I don't think it's industry related either, at least not about stifling bad reviews of new movies. There aren't enough people who read the boards, not at that level at anyway, that it would cause a significant drop in a movie's revenue. If anything, people are going to look at the title's rating or visit other rating sites. You might get a tiny percentage of people who aren't going to spend the $20 in theaters because of what they read on a message board, but that's a fraction of a fraction of total visitors. You gotta remember, for release titles there's many other sites out there that have message boards people could read. No, this is motivated by something else and it's a near certainty that it came from Amazon. It might even be some progressive millennial in a position of power who thinks they're doing good by protecting others from "harmful trolls". It might even be a legal decision due to recent lawsuits and criminal charges stemming from bullying and other online harassment. Though I don't think it's motivated by that, but it might just be. Regardless, this is a mistake and they'll realize it. At the end of the day, this isn't "preventing free speech" no matter how much you or I want to believe that. Amazon and IMDb are not government run organizations and they're free to do whatever they want, including making stupid decisions. Hopefully someone will upstage them and create an alternative that would at least show up on their radar and give them even a small bit of grief.