What he probably meant was you can copy and paste text into a translator which I don't think we should have to if the rules state it's English only. Understandable English isn't everyones first language so a ubbc button that just auto translates would be so much easier especially not be forced into downloading language packs we don't want on our phone that Android sometimes makes you do.
Machine translation isn't perfect and frequently makes mistakes, made even worse when people become aware of their limitations and exploit them. Sites are often English only for moderation reasons e.g. all the mods only speak English and getting new mods for each language is risky or impractical, and moderating based on machine translations leads to misunderstandings and disagreement.