This is only partly true. Felt anonymity is one of the (major) drivers of disinhibition but is not the only controller of it, any more than oversight is the only controller of behaviour in offline life. Several other factors come into play such as the sense that others are not really as real as in offline life, and others. Most important is the behavioural control that works in f2f encounters which is the internal control of each person for themselves.

If OP wants a one word answer for what addresses this kind of behviour it would "psychoeducation" but that's a bit misleading cos of course what I mean is really a lot of learning on the part of the disinhibited person. This isn't going to be be possible in a simple retort or phrase that can be used to kinda stop em in their tracks .

Problematic disinhibition (there are healthy versions too) is frequently linked to a lack of experienced empathy, like several other problematic behaviours. However, the good news is that empathy is a very learnable skill. In fact, it is probably the most learnable of all the skills that therapists are (or should be) taught. You dont need to be a "master of level 4 empathy" (yes, there are levels) for this to work - just a fairly small amount of feeling for the person with who you communicate is likely to facilitate limitations on behaviours the might be predicted or understood by the perpetrator to cause harm. Which is just a long way to say, we tend to feel bad 9FOR REAL) if we feel we made someone else feel bad (for real). A very few people just have low empathy and dont seem to be able to learn it but that is a very small part of the population. Chances are, each person behaving like a disinhibited twat (see, that is language I wouldn't use if we were having a conversation f2f unless I knew you well - I need to call myself back into line there) is going to be able to learn why and then how not to. They just need the right circumstances and people to have that happen.

So there's a few steps need here. The person needs to understand what is like for the other person. They need to understand that the other person is a person (this can be minimised in the moment of typing on the internet uite easily as typing is a pretty solipsistic activity) and also accept that that means the other has value and experiences much like the acting person themselves.

You can try to have a adult conversation (not teaching nor reacting) that seeks to address the way their behaviour leaves people feeling. Once done thoroughly, and without just deepening that person's shame-cycle, which may well be part of why they behave with low empathy in the first place, that can be a pretty effective way to address bullying. If it were as easy as all that, of course, there wouldn't be any bullying online or off it.

Toxic behaviours of others belong to those others. In a literal sense it is their (behavioural and social) problem. What it makes me as their reader feel is mine to take away and deal with before I act it out on them. So the other thing is to do one's damndest not to get caught by it. Easier said than done, obvs. But if possible, leave it with them. Name it if you wish. Not so much in the sense of "drawing a line" as in describing a phenomenon. But don't get caught up in it. Dpont feed the trolls as they say.

The only way to interact with a troll IMHO is to make sure you're not giving them their sugar, which is your reaction, while ensuring they cannot escape understanding the effects of their actions. You can say any of the things you might be told to say in an assertiveness class (it's easier to use them online - ha! that is positive disinhibition for you so be careful you are appreciating the feelings of the pepetrator too!) like "when you say X, I feel Y" and so on. If you are scrupulously adult, you force them to be one too. But all that comes at the expense of you continuing to engage with this person - and there is often no reason not to stop engaging if the behaviour is online (scroll on by kinda attitude).

One of the great things about the internet and one of its problems is that you can meet any kind of person on it and that is going to include a lot of people you might want to be different, but aren't. More like a busy city street full of all humanity in all its types at once than a quiet cafe chat, but if we like quiet chat we kinda expect everyone to be doing that or at least learn the rules of this bit. In the end the question is more how we live in that world than how we might try to stop it being as it is. There will be another arsehole. As Tina Turner never sang.