[WHATWG description:] The placeholder attribute represents a short hint (a word or short phrase) intended to aid the user with data entry when the control has no value. A hint could be a sample value or a brief description of the expected format.
Of course some people like examples better, others prefer an abstract description. Some people might even prefer to be given a regular expression, I don’t know.
Where can I read the user research you bring up?
What are the arguments against placeholder? I didn’t find any reasons in the article that suggests ditching/repurposing it.
Some or even many people prefering a different kind of aid is not an argument against keeping placeholder as it is now. You can have a new mechanism that you like better without dropping the option to use placeholder as it is now.