Ethernet deals with frames, not packets.
Packets are an IP concept :)
Packets are an IP concept :)
But RFC 791 dates from when the underlying L2 network was most likely ARPAnet, which had 128 byte packets. Today the distinction is (or should be) moot - if you're relying on IP fragmentation to send your large IP datagram over multiple L2 packets, you're doing something wrong. IPv6 doesn't even support in-network fragmentation.
In practice, the distinction has largely disappeared over time. Everyone I know talks about packets and very rarely bothers to distinguish between frames, datagrams and packets, because in practice one Ethernet frame generally carries one IP datagram, and everyone calls it a packet.
Yet the article uses frame throughout where technically correct, and what was important to the author wasn't that any frame was transmitted, but that they got their packet to show up correctly.