Phone snatching is handled by settings within "lost device protection". Secure folder is kinda ran with the idea that "you unlocked secure folder, between now and when your phone screen locks, you should still be holding your phone and using it, so it trusts you". There are now multiple security features that lock your screen if the phone detects someone takes it. While yes removing a feature is bad, it's probably to stop people using secure folder for something it wasn't made for. It's a really really good security at rest feature for guarding against advanced attacks.
Sorta think of it like instead of secure folder locking when someone steals your phone, protecting private apps. The locking is done on the entire phone. If someone steals your phone, everything is protected.
Having people rely on secure folder locking as soon as they leave the app might make them use actual device security features less. I have seen that a few times on here.
