This happens with any sufficiently large platform. Microsoft, Apple, Google, Amazon all offer large platforms and the developers develop a "feature" on that platform. They might come up with the same idea independently, or more likely the big one steals the small one's lunch. And the "scouting interview" happens at every level, even the smallest players dangle nice offers to goad some useful info from candidates.
Sometimes the features are obvious though. I remember developers complaining when Android got a built in flashlight toggle making almost every flashlight app redundant - and thank God for that, this is a legitimate feature of the platform.
I can't read the full article but on one hand Apple poached employees which sounds legal on the face of it. On the other hand the patents for the technology that Apple filed were not legitimate [0] according to the courts. So the issue here seems to be more that the patent review process is weak and requires a lengthy and expensive court case to clarify. Something a small company may not afford.
This isn't "just" that Apple&Co are abusing smaller players and copying products or features. The problem is systemic because Apple&Co bought and paid for the entire framework in which everyone else operates. Your elected officials, legislators, laws, rules, regulations, and courts are tailored for Apple&Co, or at the very least are heavily favoring them with very few exceptions. Until that's treated everything else is a symptom. Decades ago the kiss of death from the company I was in came from IBM. Same story, less resources to fight it in court.
[0] https://www.reuters.com/legal/transactional/court-says-med-t...