I wouldn't say that completely follows. It would certainly indicate that developing a vaccine would be harder, but not impossible.
Modern vaccine development is essentially fly fishing at this point: the amount of control and options we have with the immune response-generating stimuli exceeds naturally-ocurring scenarios.
As an example, most of the spike-protein-expressing vaccines generate / deliver modified spike proteins, distinct from those found on actual SARS-CoV-2 coronavirus.
It's triggering your immune system to produce and/or store things, the presence of which then confers resistance when subsequently exposed to the actual pathogen.
So from that perspective, the next question is, "Do naturally occurring pathogens, presented in a natural manner, produce an optimal triggering themselves?" To which the answer, as you might guess from the messiness of real-world biology, is "No."
It turns out that while amazing our immune systems are also general purpose and adaptable, and such systems can get confused, or go off on a tangent, or focus on the wrong thing, etc etc.
Vaccines interact with this system by balancing two things: (1) how do I trigger the strongest, purest immune response that's effective on the thing I want to immunize against & (2) how do I avoid triggering such a strong immune response that I convince the body to attack itself?
It turns out, with modern biology, we actually can do better than nature on (1). Even if (2) still requires some guesswork (and a lot of testing).
There were some suggestions that Covid-19 would be an exception to this somehow, and having recovered, you would still be just as susceptible to getting it again. Which, if it had been true, would have been really bad news, although I suppose it would also have meant there was no reason to wait for a vaccine, because if even the actual virus itself doesn't teach your immune system to look out for it, then there's no way a vaccine could.
But, it's good scientific/medical work to verify that it works like most other viruses, and people who have recovered, are at least almost always going to be resistant thereafter (for at least six months, because that's all the time that has passed yet, although evidence from SARS suggests 10 years or more).