I suspect this post is predicated on the assumption that most people who advocate ending negative relationships are naive, or hypocrites. I think the OP might have this preconceived notion that “people wouldn’t recommend doing this if they truly understood the consequences.” 

The thing is that everyone has their own list of compromises they’re willing to make vs. consequences they’re willing to put up with. Some people would rather compromise more, so they can avoid negative consequences. Some people would rather face more negative consequences, so they can avoid having to compromise. 

Everyone has a different conception of “acceptable compromises” vs. “acceptable consequences” and everyone thinks that their conception is universal, and that anyone who claims otherwise is naive, or hypocritical.

I’ve talked a little about this before in a different post:

Take for example someone saying “I did everything I could.”

They might mean “I did everything I could short of compromising my personal morals”

They might mean “I did everything I could, including things generally deemed immoral.”

They might mean, “I did everything I could without damaging my mental and/or physical health.”

They might mean, “I did everything I could including damaging my mental and/or physical health.”

They might mean, “I did everything I could within what I consider an acceptable level of risk.”

They might mean, “I did things that could have killed me and/or others.”

They might mean, “I did slightly more than what I would usually do.”

And here’s the thing — whatever they did mean, they’re going to assume most people mean the same thing. Everyone naturally assumes that their line in the sand is the standard line in the sand.

[…]

Or as George Carlin once said, “everybody who drives slower than you is an idiot, and everybody who drives faster than you is a maniac.”

Now me? I’m not going to stay friends with someone out of fear of loneliness, misplaced loyalty, habit, or because I think I can change them. I would rather lose a friendship than have someone stay friends with me for these reasons. I can say that with authority, because I’ve been on both sides of that scenario.

These are valid points; for me, personally, however, I reblogged the post because I found it to be a bit of an interesting mental exercise. 
This is coming from the position of fully believing in [and practicing] cutting ties with people/relationships once they become a drain and/or source of toxicity as opposed to a fulfilling addition to my life.

That being said, I do think it is absolutely important to take a moment to realize and consider and internalize that other people can and will do this to you for exactly those reasons–not in the sense that it should discourage you from doing so, but in the sense that you should use that self-awareness to understand their reasons, their needs, and their motivations; that is to say, instead of becoming angry or resentful over it [although it’s generally somewhat unavoidable; no one likes feeling like a burden and no one likes being cut out of someone else’s social circle, and feelings aren’t usually super rational anyway even if you can logically process the reasons behind something], to understand where that other person was/is coming from and either a/ not take it [too] personally and/or b/ modify your behaviour in current/future relationships [in the case of you being a drain or toxic presence on another person’s life].

So yes, I think it’s important to take a moment every so often to apply the rules and standards you have to your own life and choices to the behaviours and actions of other people. I, personally at least, can occasionally get sucked into a slight unconscious solipsism in that sense, and reminding myself of these things is helpful, and I’m of the opinion that it’s helpful for other people to do so as well.