Yes, but virtually every published peer-reviewed study will have a large enough sample size and will have done the math to make sure that it is large enough. I

Yes, but virtually every published peer-reviewed study will have a large enough sample size and will have done the math to make sure that it is large enough. If it's the first thing that comes to the mind of random HN commenters who haven't even read the actual article, it's probably also going to occur to the experts writing and reviewing the article. Peer reviewed articles aren't perfect, but it's pretty arrogant to think that the authors and reviewers are so bad at research that you can find problems with them without even reading them.