The reason is simple — Snapchat added Snap Map so that you’ll use Snapchat more often.
If you use Snapchat more often, you’re more likely to see the advertisements that will eventually be embedded into the map. More advertisements seen means more profit for the company. More profit isn’t bad, but it’s worth pointing out that it is the primary motivation for companies to add new features to social media apps. Your well-being is a secondary concern.
Every tech company in Silicon Valley is at war for your attention. Your attention is your most precious resource, directly determining your well-being.
Be less concerned with stalking. Be more concerned with what you do with your attention.