“Stolen mode” isn’t really a thing with Activation Lock; Apple correctly assumes that the average victim of theft isn’t alert enough to flip some switches in iCloud.
Thieves know that iPhones are useless - now even more so - in their default state, and can only be removed from that state with deliberate action from the legitimate owner.
That has real life value, and so your accusation that it “only exists to pad the bottom line” is wrong.
This doesn't mean the theft lock feature itself doesn't have a purpose, just that making it confusing to remove was intentional to decrease hardware reuse.
Send them a locked device, they’ll send it back because it’s unsellable.
No legit place is buying locked devices. Which means they don’t sell them.
Of course you are. If anyone except the original owner can remove the lock, it’s more valuable to a thief. (Same if the owner can be tricked into removing it or do so accidentally.)