Yeah, those requirements are quite steep for what Parler does. That being said, it is actually incredibly hard to scale any product that sees a sudden massive influx of users, media attention, and conflict like this. I mean this from a purely technical standpoint.
If your customer base is doubling every few weeks, that's simply not enough time to hire more engineers, onboard them, and get their resources focused on optimizing the stack to improve efficiency. It's also way more realistic to scale up your infrastructure in the short run until you know you've stabilized at a point where you can purchase and operate dedicated hardware to offset the steep margins cloud providers charge.
On top of it all, their product itself seems off-putting to a large portion of tech workers, which would make hiring talented individuals even harder.