Have you ever had a conflict with a friend or lover, and the person that you're venting to goes, "Well if they wanted to, they would?" The "would" in question being showing up for you, texting you back, or just generally maybe being more present?
I guarantee you they told you this because a lot of us tend to settle for our needs not being met, especially when you come from an abusive background. They want us to up our standards and find people who actively want to be there instead of blasé folk who clearly don't care about us. In this regard, I believe this statement to be true. However, depending on the situation, this statement lacks a lot of nuance that in some ways can lead to ableism.
I live with attention-deficit/hyperactivity disorder (ADHD). Every day I have thoughts to text, call, or message people, especially people I haven't spoken to in a while. Do I do it?
Sometimes, sure, but most days, no.
It's not because I don't care. I genuinely live with a processing disorder that causes forgetfulness and executive dysfunction. You could be on my mind all day, and I may want to reach out to you and have full intention to do so, and simply just struggle to do the damn thing. It's not because I don't care or I don't want to. I have a clinical reason for why reaching out is harder. If someone were to come to me and say "You'd be there if you wanted to be," I'd be so hurt because I do want to be present, but my brain makes it hard to be.
On the note of your brain making things hard - there are a myriad of physical and mental health conditions that can cause fatigue and lack of energy. We've talked about the spoon theory, fork theory, Noodles the Pug (TBT) theory, and all these other theories that explain to abled folk how health can impact what we're able to get done in a day. On a low energy day due to my health, communication can become a very hard and stressful thing to manage, especially when you may have to mask and force yourself to do it for the sake of work.
Perhaps someone has severe anxiety and that's why they don't show up for you in moments you want them to. What if your favorite thing to do is karaoke, but they have debilitating social anxiety and thus they refuse to go.
It's easy to internalize someone else's silence or lack of communication as a personal slight, and it's harder to realize it may have nothing to do with you at all and instead it's just them managing their life and their health.
You deserve to have your needs met, but there's a difference between someone who doesn't care to meet them and they can, and people whose health conditions are set up in a way that makes it harder for them to do so. You can ultimately decide who you want to retain in your life, but don't be afraid to offer compassion and ask people for clarification.
If they wanted to they would, except maybe they just can't, and that doesn't make them a bad person.