VATSIM is strongly based on the American system which doesn’t really have the concept of AFIS that you will find in a lot of European countries, so the vACCs responsible for these airspaces have to find workarounds. I imagine in most situations, this workaround will be similar to what VATGER had not so long ago: get your S2, then a separate AFIS endorsement, and only after all that you are allowed to open an AFIS position - quite frankly, it’s a luxury that you can get an AFIS-only endorsement with your S1 at all. And most people on VATSIM who get a controller rating want to control and not just provide information, so in 99% of cases, this does not pose an issue; the small amount of people who, like you, only want to staff AFIS positions will still need to pass the ATSim Test as required here to get the S1 rating (which you need to be allowed to open one of these positions) and to do that, you need to be able to answer questions only relevant to people who want to control. And even then, that knowledge will help you get a better understanding of the ATS environment.
I also don’t really know why you think you need an additional lesson for the introduction into ES. If you read the ATD guidelines and the AFIS-only thread, you would see that you are allowed to open an AFIS station as soon as you have passed the ATSim and moodle tests. Nobody “demands a further basic lesson”. You don’t even need to know a lot about Euroscope. You can just connect, maybe set your vis center, then use the towerview in your own flight simulator, et voilà . If you have a radar station above you, you don’t even need it when staffing an AFIS airfield with IFR procedures. Of course, familiarizing yourself with the software can’t hurt, so sitting in on a basic lesson designed for controllers or getting a mentor to spend 30 minutes of their time to show you the basics wouldn’t be bad, but - as I said - there is no hard requirement other than the AFISO basic lesson.
VATSIM does build up the ATC training “bottom up”. You start with TWR (in some places you may only be allowed to control GND or even DEL before that), then APP, and then CTR. This is already not realistic for multiple reasons, but that’s another topic.
Now, if we took your proposition and changed our training system to start at uncontrolled fields, that’d result in exactly what you are complaining about, just the other way around and affecting way more people: everyone who is only interested in controlling would have to learn all this - to them - unnecessary AFISO stuff. It’s much better to have the small minority of - I imagine - way less than 1% of members interested in/holding a controller rating jump through one or two additional hoops than making becoming a controller harder and less attractive for the vast majority. Because of this, I’d also argue that your judo analogy is not fitting at all: I don’t know much about martial arts or what the judo belts mean, let alone how you get them, but a more proper analogy would be that everyone is going yellow → orange → green, but you are in a situation where you want to learn just the one move required for the orange belt, but are not interested in the move required for the yellow, let alone green belts.
Now, I’m sure the VATGER ATD - or probably even more so the VATEUD ATD as from my understanding they are responsible for the ATSim test requirement - would love to hear your feedback, but that’s not really something VATSIM as a whole can do anything about (other than completely overhauling the station system and introducing separate AFISO logins and AFISO ratings).
Also, please don’t call it “AFIS controller” or “controlling”. AFISOs (=Aerodrome Flight Information Service Officer) don’t control, they provide information. 