In my experience, when social justice warriors are "criticised" it really is
an attack on them, either overtly or because it is a clear (yet often inadvertent) support of a status quo that actively oppresses a demographic that they may well belong to. After the hundredth such "criticism" that week they may be disinclined to provide another detailed one-on-one education that requires several new concepts to be imparted and a very rare willingness of the so-called "critic" to listen and understand. But I can say with confidence that this is not because you hurt their feelings, don't imagine you have that power. They will be quite used to hearing your points every single day, and your wearyingly familiar input, however it may look, will be the least of their worries.
They may also be uninterested in a calm and measured discussion of the topic when the subject of the exchange may well be nothing less than their intrinsic value (and even status!) as a human being. I learned that the hard way by being on the asshole end of that conversation, and it was eye-opening. I can assure you that the real target of criticism in that discussion was me, and I paid attention. It really does hurt when your self-identity is as a good person with progressive ideals and you are made to recognise how many backward, harmful and unhealthy attitudes and views about people you really have and never even think to consider. But I can't claim to have understood that conversation without putting my meagre hurt in perspective, or realising that my feelings with regards to this sort of thing really do not deserve to be protected, and that most of my hurt stemmed from the entitled opinion that they should be.
I was going to go into the main topic of talking criticism after that, but it turned into it anyway. Some people really do need to toughen up but that's something that maybe we should help each other do rather than just declare that it should be that way. But a lot of us are much less tough than we think, we simply don't get criticised nearly as often as we should (often because everyone around us is making the same mistake), and some of the people we think should toughen up are already, by necessity of circumstance, some of the toughest people alive. Don't confuse passion and justified fury for hurt feelings, in some cases that may even be projection on your part.
And really, this: don't criticise unless you really, really
know the topic. While being aware that the Dunning-Kruger Effect
my be in effect when you think that you do.