Yes, and not just on this site.
If so, did you know why? Did it bother you? Did the "threat" cause you to modify your behaviour in anyway?
Several years ago, I was ignored by a few people because I was probably crossing a line and unintentionally harassing them. That did make me re-evaluate the way I interact with other people.
Most of the time, people ignore me because they're upset over something I say or my worldview. Sometimes it does bother me, because I did not mean to upset anyone, but I understand. Blocking/ignoring other users can be a healthy way of limiting information overload and from seeing content that produces nothing but pain for you. It can be a genuine feature of self-care, or even just a way of respecting your own time.
I understand that not everyone will agree with me and some people will disagree with me so strongly that they're completely disgusted by me and what I say. I think that's just a part of being human. I try not to let myself reach that same level of passionate disgust about anything because it's unproductive, but that takes serious discipline and even then I still fail sometimes. So I get it.
Have you ever "threatened" to put someone on ignore? Why did you do this? What result did you expect? Did it accomplish what you wanted?
In my private life, I liberally cut contact with people that I just don't feel like talking to anymore. Often, I will send them a message first trying to explain that it's just because I'm not a sociable person, don't really feel sentimentality towards others, and feel sort of suffocated by relationships that get too close.
Some people understand that it's just the way I am. A lot of people ignore everything I say and take it personally, beating themselves up over not being "good enough" for me, whatever that means, without realizing that the problem was never them. I honestly hate that, but there's not much I can do if they choose to misinterpret my cold, dismissive-avoidant interpersonal style.
I have threatened to put people on ignore when I think they have an inflated sense of their importance to me, just to demonstrate that they don't have the power over me that they think they do. Usually, this works and I don't actually have to ignore them. Sometimes I do end up blocking them. Either way, I'm no longer subject to their behavior, so I win.
On RF, though, I make it a point to not ignore anyone because I'm here specifically to broaden my horizons and open myself up to people who disagree with me. I don't want to end up in a self-made echo-chamber. When I find myself really wanting to ignore or block someone, I'll instead try to have a discussion with them. This is not something I would ever do outside of this forum in my personal life, where I am more reserved and aloof.