I think some people genuinely don't understand what Japanese BL labels mean when they upload and label it. "Shounen AI" is specifically BL without any sexual content, whereas BL with sexual content is called "Yaoi." A manga can't be Shounen AI plus Adult or Mature at the same time, that doesn't make sense. Especially when there's a specific word for BL that has that content.
I think some people genuinely don't understand what Japanese BL labels mean when they upload and label it. "Shounen AI" is specifically BL without any sexual content, whereas BL with sexual content is called "Yaoi." A manga can't be Shounen AI plus Adult or Mature at the same time, that doesn't make sense. Especially when there's a specific word for BL that has that content.