The best practices that encourage you to minimize content and maximize whitespace on your screen. To change text for icons. To hijack the scrollbar. To replace perfectly good default controls with custom alternatives that look prettier, but lose most of the ergonomic features the default controls provided. To favor infinite scrolling. Etc.

Some "best practices" articles discourage all this, but in my experience, that's ignored. The trend is in ever decreasing density.

It all makes sense if you consider apps following the practices I mention as sales drivers and ad delivery vectors. Putting aside the ethical issues of building such things, my issue is that people take practices developed for marketing material, and reapply them to tools they build, without giving it any second thought.