9.1Start with the problem API-led architecture solves

Bad architecture:

Web App ─────→ Salesforce
Mobile App ──→ Salesforce
Partner App ─→ Salesforce
Billing ─────→ Salesforce
Support ─────→ Salesforce

Then later:

Salesforce field changes

and suddenly five integrations break.

Worse:

Web App → Salesforce
Web App → Billing
Web App → ERP
Web App → Marketing

Now every consumer understands every backend system.

That's tight coupling.

API-led architecture inserts reusable abstraction layers.