Unfortunately, the post is slightly incorrect. Your character automatically calls out when they see the dropped spike, but not the spike carrier. There's also an announcement that plays for both teams when the spike carrier is killed.
Edit to address your notes about depth and spotting the spike carrier:
Goes without saying, but when defenders know the location of the spike it usually tips the balance of the round in their favor, enabling more confident rotates, stacking, and more focused defensive setups.
We used to have an announcement that played when a defender spotted the spike carrier, but it had a few problems:
- In a game with drones, cameras, and teleporting/dashing characters it was really easy to catch a glimpse of the carrier and get that important info with very little effort.
- Sometimes a player would not know they had the spike (e.g. someone grabs it and throws it onto a teammate while they have the buy menu up) so they wouldn't always position thoughtfully - or simply wanted to peek - and would inadvertently give away the info
- Many of the higher-skill players drop the spike in a neutral spot (robbing the defenders of the carrier killed notification while they try to get picks), so the feature became a bit irrelevant at higher levels of play anyway
As for the depth you mention, you can definitely still achieve that effect by dropping the spike in a conspicuous spot, waiting for an enemy to spot it, then bailing to another site.
Concealing the spike carrier until they are killed relieves a little pressure on attackers to have to constantly worry about who has the spike and if they are handing over critical info (often without knowing it) for as little as a pixel peek from the defense.
Conversely, the carrier dying is an earned and clearly defined event for both teams, enabling them to confidently react.
Hope that helps shed some light on the thinking. Thanks for bringing it up!