The phrase "strongly-held beliefs" brings to mind XKCD's "clinically-studied ingredient"[1]: flat-earthers, neo-nazis, and GWB's CIA strongly believe(d) in all kinds of things. I'm not sure being "strongly held" makes a belief undeserving of denigration.
I think most people (including myself) find virtue signaling annoying for two reasons: first, it's usually conveyed in a smug, self-righteous, and even accusatory attitude, and second, because it rarely contributes anything or furthers discourse. In fact, it almost always stifles it. It's useful to call it out for the discourse-limiting technique it is, right up there with whataboutism, sealioning, etc.
Secondly, there's a belief hinted at in your justification that one must have an opinion on everything - that "silence is violence". You're either for (or sometimes against) the Current Thing, or else you're a fascist puppy-kicker who wants the terrorists to win. There's no in-between, no nuance, no additional considerations allowed. (See also: "That's a [republican|democrat|communist|nazi] talking point!") Virtue signalers communicate in talking points, betraying their tenuous grasp of a subject they have (ostensibly) strongly-held beliefs on.
Furthermore, in my personal experience, the loudest virtue signalers always seem to be the worst humans, so there's a kind of stomach-turning hypocrisy when (e.g.) you see someone who you know kicked puppies all through high school and college never shuts up about what a dog person he is (because dogs are good and people who don't like dogs are Bad; therefore, they are Good because they like dogs). Or the dirtbag who creeps out girls constantly posting feminist memes, illustrating that women can definitely feel comfortable around him. That is, it's not the dogs or feminism that's disgusting.
The way that "wokes" (where "woke" = "shitlib", shifted left) employ virtue signals is distinct from leftists engaged in debate, starting with the complete lack of dialectics. The conversation exists not to exchange information, reach an agreement, elucidate facts, or any of the normal reasons people discuss and debate things. Instead, it appears only to serve the external image projected by the speaker/author, whether erudition or to assert they're a Good Person™.
Part of it can be blamed on "eternal September" of sorts, where each year, a new group of freshmen are learning for the very first time that the world isn't as simple as their parents and high school teachers taught them. That sometimes, what's written was written for political and ideological rather than factual purposes (e.g., Columbus). It should engage a healthy dose of skepticism or criticality - even outrage - but the trend here in America seems more contrarian than critical, and it manifests in daft conclusions[2].
To further illustrate my point, I have many friends and family that are Spanish-speaking-born-outside-the-USA hispanic. Many of them work with other immigrants from all over the world, and I've sat around with people who each speak a different language and had totally reasonable conversations on all kinds of hot-button issues. We share, we learn, we shake our heads at each others' misunderstandings, and sometimes even call each other names. It only becomes a hostile shitshow when a white, liberal, middle-class, college-educated dork shows up and starts trying to rank Mexicans, Puerto Ricans, Dominicans, Nigerians, Ugandans, Albanians, etc on their overly-simple oppression ranking scale, or shitlibsplaining to a native Spanish speaker about how they should use "Latinx" because Genders Bad. Usually, they just get laughed at, but it's devolved into some pretty heated situations that could have been avoided simply by shutting up and listening, instead of explaining to Ugandans and Haitians that their struggles are basically the same.
Another anecdote was a local in town who routinely inserted themselves into things that didn't concern them, often with a great sense of moral superiority. One day, they appointed themselves in charge of telling homeless people which side of the street they should be on. After lecturing the homeless white lady on race and that she needs to give up her spot to the black homeless man, she informed him that he assaulted her and took her spot, and that's why she was cry-screaming on the corner. He let out a literal shriek and tried to back out of it with a feeble "can't we all just get along" before the homeless guy assaulted him for interfering at all.
It was "her" spot. She sat there damn near every day. The dude was acting erratically and ended up going to the hospital - but the facts didn't matter - his mental health didn't matter - her physical safety didn't matter - only this simple, stupid, binary scale of oppression (to be created and enforced by you-guessed-it: overeducated and underemployed upper-middle-class white kids), and - presumably - the ability to go home and post on social media about what a Good Person™ he was to teach this homeless lady about her privileges he just learned about last semester.
Their blatant ignorance and racism shows through when they start generalizing about these peoples' countries, cultures, languages, etc through their own distorted lens; they expose their colonizer parts by lecturing South Americans on how they should change their language to match The Correct Idea of Gender; flaunt their internalized white supremacy by asserting themselves as the ad-hoc police, etc, etc, etc. On the bright side, at least they understand they're not allowed to call the cops if they get punched in the face by anyone with darker skin or a thicker accent than they have.
In short, it's so often transparently performative and done with such a repulsive attitude that their lectures are frankly beneath contempt, even if some of their talking points are occasionally correct/agreeable.
[1] https://xkcd.com/1096/
[2] https://www.realclearpolitics.com/articles/2023/10/29/the_disfiguring_prism_of_oppressor_and_oppressed_149977.html