there's no way to measure the number of people who have been further entrenched by YET ANOTHER PROGRESSIVE MOVEMENT where the tribal actions of those belonging are geared towards social climbing within the cloister as opposed to outreach to those who don't already agree with them.
Increasingly, the modern left seems hellbent on demeaning "those people" on any number of topics, from culture war, environmentalism, COVID. They can't meet people half way in the hopes that some, in turn, will open their ears to what they have to say. Instead the entire movement - from BLM, to the pro-vax crowd, the pro-trans movement, the climate change movement, is merely to sneer down anyone who even slightly disagrees with them, including fellow leftists who might be slightly out of lock-step.
This is not a political movement that can grow in any meaningful way. It means to humiliate, dominate and reign it's superiority over others. And for now - they have the power of the media, hollywood, academia, most HR departments and such on their side that helps them feel comfortable in this ... lack of a political strategy.
But when their goals and the goals of corporate america don't align, just watch how this "strategy" will work out for them.
YOu have to actually treat people... like people, even though you disagree, to build your movement.
That's the hard work of politics.
The left is insulated by a corporate system who's tricked them into thinking their goals are aligned. They're not.
There is a deep partisan divide at this time in our country. Are there really that many people in the middle, the undecided voter, who were going to vote for Trump but changed their mind and voted for Biden because people online were nice to them? I have a hard time imagining this.
I agree that the level of discourse is at an all time low, but I disagree with a lot of what you're saying because it paints with a super broad brush and also treats base insults and sneering as though they're the sole domain of the "modern left". It is a mistake to confuse the loudmouths on Twitter (where I presume you're seeing the majority of the chest puffing and punching down) with the actual humans behind the movements you mention.