Thank you for your response, and I try to understand your logic behind this. Like you, I have strong research background spanning several decades. First of all, participant compensation should not be the primary concern for research design. So this argument is out.

Secondly, Medium is a global company. If an experienced person selects a sample, it must be representative of the population. So the USA only sample does not make sense to my research experience. I worked for an extensive group of multi-cultural teams much more significant than Medium and always included some representatives from each country.

If they select US only people, it does not make sense to send email to everyone and disappoint people.

You mention market research, but the letter says it is designed to set the future of creators. So I assume that it is qualitative research. Your points for market research make sense but not for a qualitative/strategic initiative.

Unless Medium discards all other nations and plan to go with the US creators, this sample does not make sense.

This survey looks like a mess from every angle as many people whom I conversed with recently. I am surprised you are behind it. But I respect and value your opinion, views, and kindness to respond. We can agree on disagreeing.