A real life example is Instructure, which makes Canvas (which is agpl) but has other proprietary services that interact heavily with it. It's never been a problem
Don't be silly: a web server is not distributing a web browser, and thus when you visit news.ycombinator.com, they don't have influence over whether you do that via netcat, curl, or Awesome AGPL Browser 1.0
If, however, they used https://git.deuxfleurs.fr/Deuxfleurs/tricot to serve the http request, then AIUI the AGPL entitles you, as a "13. Remote Network Interaction; Use with the GNU General Public License. (https://opensource.org/licenses/AGPL-3.0)", to ask for the source code of tricot and potentially any systems that it subsequently interacts with
I'm certain I'm going to regret posting this, given how hot-button the AGPL is in every one of these threads
Can you cite cases that have established this as fact?
IANAL, and thus far my life is worse for any interaction with the legal system
When MongoDB was under the AGPL, your application wasn't under the AGPL if you connected to it and asked it to do queries.