I've often heard Bitcoiners compare BTC/LN to TCP/IP. Perhaps this comparison is no longer useful since the new standard for web protocols no longer includes TCP.
I think this is a useful lesson - because we still call it "the Internet" and yet the protocol has quite evolved over the time.
SPDY being pulled in as HTTP/2, QUIC as HTTP/3...
I still remember optimizing websites performance because of the issues with HTTP/1.1 and trying to fit the first response in 1500 Bytes MTU, so we save another roundtrip during the slow start.
"TCP/IP" is a suite which includes UDP and these TCP-like protocols implemented in user space are encapsulated with UDP. So it's technically still correct, though it's not as snappy of a saying if you have to add "but actually"...
UDP is not included in TCP/IP. Maybe that's what people mean when they shorthand say TCP/IP. But technically UDP is an alternative to TCP and also builds on top of IP.
HTTP/3 still uses IP and all future versions probably will. Maybe one day better solutions than LN will show up, but considering how long it took for a competitor to TCP to show up, I think we have some time left;-)
random thought: maybe Monero then is ICMP: not that visible or relevant but still useful in certain situations.
I do think the internet stack is in dire need of modernisation. But moving TCP functionalities higher up the stack is not the thing that needed improvement