I do think these platforms are getting better at weeding out these problems, but things like review bombing as a concept are also often used to discount audience opinion
Sorry, that's nonsense, complete and utter nonsense.
Review bombing is often used to discredit
random polls of users on the internet which commercial websites say represent audience opinion. Which is perfectly reasonable.
That's very different from actual, real, properly-measured audience opinions!
You can't "review bomb" any actual polling of actual audiences, conducted properly! And that polling does exist - one example is CinemaScore. It's been around since 1979. It's worth noting one thing - since the 1990s, it's very rare for an audience to give a movie worse than a B, but within the B-, B, B+, A-, A, A+ grading available there's still a decent degree of nuance.
It's not flawless - they only (? or that's the main thing) use American audiences, which gives it a hilarious pro-Christian-themed-movie bias (easy to account for), and apparently Americans really dislike thoughtful or weird movies (but even then, a good thoughtful/weird movie will usually do better than a mediocre or bad one, with the odd exception). It's certainly much, much better at correlating with the actual success of movies with audiences (relative to marketing etc.) than stuff like RT's audience score.
en.wikipedia.org