You're not alone in this, at least - there's been quite a few highly qualified Hacker News members posting about the experience. Don't take it personally. But it still really sucks
If their KPIs prioritize volume of candidates contacted at the expense of following up with qualified candidates, then their KPIs are mis-aligned with how the business makes money.
Mind you, I'm not saying you're wrong...
1. The recruiter got fired between reaching out and the call.
2. The recruiter discussed you with a hiring manager, and it turns out the hiring manager didn't think you were a good fit for the role.
3. The role got eliminated, and the recruiter just found out about it.
4. The recruiter is disorganized.
5. The recruiter had something else come up during that time slot, and decided it was easier to ghost you than reschedule.
Happened to me.
Some call me a year later with a job opening and I take those as just an opportunity to de-rust my interviewing skills, and maybe a bit of catharsis, no expectation of moving forward. On the more selfish side, I just enjoy the chat, recruiters are pretty and they make introspective questions I don’t get to answer often.
Some offers move forward, some don’t, I got my last 2 jobs that way (8 years). Not a programmer btw, I’m in IT.
Any ability to wear multiple hats.
Any customer service skills to go along with coding ability.
Any trackable personality, so keeping you satisfied, and otherwise working with you isn't guesswork.
More?
What tends to happen is the recruiter will be recruiting for a role, they come across your profile and think you'll be a decent candidate. They'll reach out and arrange an initial call or suggest that they'll put your CV/Resume forward.
However, things don't always proceed from there for several reasons... Sometimes the client decides they're no longer recruiting for the role. Sometimes the client gets a large number of profiles to review and will some what randomly select a few good ones and reject the rest. Sometimes the recruiter themselves will find candidates they feel are more appropriate so won't proceed with your application. And on rare occasions other things might happen like they'll be in meeting that has overran or be off sick so will just miss the meeting.
From what I understand because a recruiter might be talking to numerous candidates for numerous roles at any one time the overhead of contacting them all to say something like "the client doesn't want to proceed with your application" is simply too high. Additionally, often candidates don't really care anyway because at this point they've already applied for several other roles. This is especially true in tech where historically candidates might decide to ghost recruiters after getting an offer for another role.
I'm not saying it's nice, but you shouldn't take it personally. It's just a side effect of candidates applying for multiple roles, recruiters recruiting for multiple roles and clients reviewing multiple candidates. However, given the tech job market is weak right now it's not uncommon for recruiters to receive upward of 100 applicants per role (a lot of which are spam or completely unsuitable) so they're obviously not going to be getting in touch with candidate explaining why their application won't be proceeded with.