"What could be a simpler networking concept than TCP's RST packet?" There are twelve RFCs that cover the TCP protocol. They had to write a guide to traversing

"What could be a simpler networking concept than TCP's RST packet?" There are twelve RFCs that cover the TCP protocol. They had to write a guide to traversing them all (RFC7414), and that guide references 128 other RFCs. I doubt we can expect any aspect of a particular implementation to be simple. As more products emerge, their functionality diverges and inconsistencies appear. Unless you test your product against someone else's, assume there will probably be unexpected behavior, no matter what spec you're following. (It just gets worse with the intermediary devices, as they're not even a plain-old TCP stack anymore; now they can include a NAT implementation, routing, a firewall, an application proxy... the complexity becomes dizzying)