Almost every reaction that is unreasonably mean is just called toxic. The definition is very vague and encompasses a lot of things. The examples you list are fairly toxic, but there's a lot more.
It's not just responsibility. The main issue is just being mean. If you were talking with somebody face to face and a problem arised, they would probably try to explain what went wrong. But in the game it's like they can't be bothered to even talk, they just rage. A toxic player will basically skip all cordiality and jump into blaming and cursing, instead of just talking like any normal person would. And of course, they never admit their own fault.
I've seen really bad players that play like shit, don't recognize their mistakes, and don't try to help the group, but they can still be nice when they speak and have a positive attitude, so they don't feel like they're toxic, they're just bad players. Being irresponsible and being an asshole can be independent.