I'm pretty sure this isn't true. Just take a look at data of American BMI over time[1]. I don't think you can explain that away as "people are tall" (BMI takes height into account) and muscular, with a straight face -- very, very few people have BMIs over 25 due to muscle and very, very, very, _very_ few people have BMIs over 30 due to muscle. I think most people's natural judgement of overweight and obese are correct and for the vast majority of people it accurately buckets them into overweight/obese classifications because they are.

[1]https://conscienhealth.org/wp-content/uploads/2018/09/BMI-Tr...