I always took it to mean where you *begin* rather than when you are a developed player you move away from beginner stuff. See #21 above.
Most Recent
Forum Legend
Following
New Comments
Locked Topic
Pinned Topic
Modern existed. It was Steinitz.The modern era of chess probably starts with him.
https://www.newinchess.com/media/wysiwyg/product_pdf/3718.pdf