Your customers keep asking for integrations
Each one looks like a week and turns into a quarter. OAuth consent and token refresh. Pagination and rate limits that differ per vendor. Retries, replay, and the question of what happens when a third-party API is down for six hours. Per-tenant credential storage, and the security review that follows it. Then the second integration arrives and none of it generalizes.
And it does not end at shipping. Someone has to see which customers connected what, whose credentials went stale overnight, and why one tenant’s sync failed at 3am - per environment, per user, forever.