Because when steps are added the naive engagement metric trends upward. The owner of the temperature control or the hamburger menu can show their boss that people are looking at and using the “product”. More taps, more time. It’s a data driven decision making fallacy.

Users want to spend as little time engaging with the UI but that’s hard to measure. The best way to minimize engagement time would be to just remove everything. But then there’s no data. So the thing that can be measured is chosen.

When people learn the UI the engagement metric trends downward and a new UI is designed which “fixes” the “problem”.