There are anarcho-communist instances here, but the .ml admins are literal bolsheviks. As in, authoritarian communists who are notoriously all about that ideological purity and repression. You can find plenty of leftist comms here where people still shit on .ml for being authoritarian.
I'm not saying that's you, because I've met the occasional .ml user who just wasn't aware when they made their account. But by and large, when you see an .ml user, it's usually little better than a troll. Hence the stigma, incase you start noticing a pattern.
I'm not saying you're evil for believing in communism. If we were to discuss Marx philosophically, I'd agree on a lot of points. I generally like Merleau-Ponty's takes on Marxism. But I will continue to shit on any leninists out there when I encounter them.
It's good to know you were joking about the robot slaves, thank you for clarifying. You should know that most people here won't respond well to "jokes" about slavery.
For the rest of your comment, thank you for finally saying something intelligent. You're right, solar isn't literally infinite. Perhaps I should have said "virtually infinite," as once you have the infrastructure in place you can produce as much as it can capture without consuming additional resources, aside from maintenance.
A skyscraper with solar panels covering its southern face can produce a lot of vegetables. Sure, maybe carb-heavy vegetables still need to be done outdoors, but a balanced diet requires more than carbs. And producing vegetables in vertical farms lets you do it much closer to the centers of population, eliminating some of the needs for transportation and storage.
Grains and legumes might still need fields, but those also keep better and you can easily produce enough to store to make it through the following winter while still keeping a surplus. That's harder to do with leafy greens and other vegetables, which are still necessary for balanced nutrition.
"you just put it in nature and harvest all the basic things directly there using minimal energy" is a really bad summary of agriculture, though.
And not everywhere has enough rainfall to produce crops exclusively from catchment, especially now with glaciers melting and rivers going dry. Circular systems that can reuse moisture will be increasingly important as the world heats up.