Metrics are bad when they’re badly aligned or a vanity metric, but also meaningful metrics or even core metrics can be harmful.

An example of harmful metrics could be webpage statistics when learning in the open.

Reference

Ries, Eric. The Lean Startup: How Today’s Entrepreneurs Use Continuous Innovation to Create Radically Successful Businesses. 1st ed, Crown Business, 2011.

Highlights or timestamps

The Lean Startup

many startups give in to the temptation of using vanity metrics, flattering but useless or even harmful metrics that make a company look good but don’t help bring it closer to its goals.

— ^ecf005 from The Lean Startup