In the modern age (and forever, probably, but more quietly /
less permanently), we are defined by what we're outraged by.

Some of that is just human nature: obviously we don't raise our voices and scream about the things that are okay. (We certainly should practice gratitude more often, of course)

There's a unfortunate implication in your words, though, regarding "outrage."

Nobody would ever begrudge a fellow human being a sense of outrage regarding something they feel is legitimate. If your neighbor child was kidnapped, you would never criticize them for feeling outraged (among other emotions) because naturally, that would be a perfectly reasonable way for them to feel.

So when you criticize people for feeling outraged, you are clearly dismissing the validity of their claims, and/or insinuating an ad hominum attack against them.

Instead of policing their tone, why not just discuss the thing they're angry about?

Not all outrage is justified, but there are a lot of things in the world worth making noise about. Some are life and death.

But that's orthogonal to the observation that it seems true that
we simply can't have a conversation anymore about certain trigger topics.

Two observations.

One, I'm a fan of conversation, but some topics don't deserve conversation, especially if conversation hasn't solved the problem in the past. With the benefit of hindsight, we can look back through history and spot plenty of these. There were plenty of people who said, "hey! let's not get all uppity about slavery! let's really think hard about this!" and history does not look kindly upon them. There is no middle ground there and no compromise possible. Most issues are not so clear-cut, but some are.

Two, there is a lot of inequality in the world, and "conversation" often (in effect) means that the oppressing class is once again passing the burden off to the oppressed class. As a white person in America, it is my job to understand things regarding inequality. It is not black folks' job to explain it to me. Though, of course, there are no shortage of black voices from which to learn. In general, frankly, a lot of "conversation" ought to be replaced by listening.

He mustn't realise how much of the repression of women has simply
been normalised for him.

I certainly don't have any opinions on you, personally!

But yes, an awful lot of bad things have been normalized within us.

There are really two ways we can react to that. We can view those realizations as attacks and attempts to "guilt" us. Or we can see those as opportunities to get better.

Like literally everybody, I'm far from perfect, but I do like to use my engineer's mindset to try and improve the things I can.

Whether it's a symptom or a standalone issue isn't really important.
The point is that it's not useful as a tool for beneficial societal change,
instead it's a tool for gesturing vaguely and it's a crutch that we lean on
so as to not need to truly engage with or wade into the uncomfortably
nuanced grey areas which naturally surround every issue.

Ah, the ol' "bumper sticker activist" criticism.

Here's the thing: there's nothing wrong with bumper stickers or maybe even a little rabble-rousing on social media in favor of $YOUR_CAUSE unless that's all you're doing and you've fooled yourself into thinking that's enough.

Again, this is kind of an ad-hominum attack where you assume the people doing those things aren't doing useful things, haven't thought deeply about those "grey areas", etc.