Or that the particular vertical just isn't big enough to warrant their focus. A $20m MRR is great for a small SaaS but isn't worth the time of any FAANG.
For Blackberry, it was way more than just the keyboard. And the whole MS-Nokia thing is a whole different story, because both screwed up really bad here, botching the potential shot at owning an Android / iOS alternative.
It's usually more that FAANG doesn't believe in that product.
MS & Blackberry seemed pretty certain that keyboardless smartphones (the iPhone) weren't the future.
That turned out to be a really bad bet.