I suspect if there weren't needs to test mining across the internet signet+regtest would have just replaced testnet completely in Bitcoin Core by now.
Here is a great example from the Bitcoin Mailing list today (
https://groups.google.com/g/bitcoindev/c/Zx_NMqZH65Y/m/LV5zE15qAQAJ)
PS If anyone would like to test this on signet, I'd
be more than happy to help. I couldn't get my OP_CAT
transactions mined for some reason so i stuck to regtest.
Response:
inquisition.bitcoin-signet.net was down for a few days when you posted
this, due to running out of disk space, which probably would have made
getting txs relayed pretty hard. You'd probably have more luck now.
Most people, I think, are in this space to avoid centralized points of failure.
It's an option... sure, but not a replacement, and for good reason.
"Sorry global testing is down, my bad, guys." is unacceptable. I understand it happens, but Bitcoin fixes that(?)