It’s required by the CoC. You agreed to this when you signed up to VATSIM.
The VATSIM User Agreement clearly says a user agrees to be bound by the terms of the VATSIM Code of Conduct. The CoC is very clear in B5. Pilots flying through uncontrolled airspace shall monitor VHF radio frequency 122.800 or other designated “UNICOM” frequency until they come under air traffic control coverage.
Why is this so hard to understand?
+1. And using websites to “monitor” traffic is completely unrealistic. In the real world UNICOM is used extensively, and here in VATSIM one of the mantras is “as real as it gets” which is, I think, why the BoG has that rule. We don’t want to let VATSIM become a video game, even though increasing numbers of members treat it as such.
just having a radio tuned to 122.8 so you can get text should suffice as “monitoring” while enroute
my main complaint is the lack of usage AT ALL for terminal operations. people landing, taking off, just completely oblivious. just bad airmanship all around. what prompted my original post here was last weekend landing at ksfo, i announced twice on final. including 1 mile out as i saw some dummy line up right in front of me. why he didnt even LOOK OUT HIS WINDOW and see a big 777-300ER a mile away, or at least a tcas target showing +02 and maybe think twice i do not know.
anyway, i ploughed right through him hoping he had his crash detection on.
That in my eyes is worse than the “dummy” actions. Deliberately flying into another aircraft, if that isn’t a breach I give up.
Where do you draw the “realism line”?
Is it realistic to have no ATC from the belgian-french border all the way down to southern Spain in IFR-only airspace?
Is it realistic to allow pilots time acceleration on the network?
Is it realistic to have no one “in the cockpit” for half an hour straight?
Is it realistic for ATC to have the ability to send a pilot a message to tell him the frequency he should contact now?
Why are there even programs and websites where you can look up which ATC are online? There’s no such thing in the real world either, afaik.
Why does VATSIM not prohibit the usage of simaware and the likes. I mean… it’s highly unrealistic, isn’t it? 
Oh, I’m fully aware of all the necessary workarounds which help pilots and ATC to use VATSIM. But I think I draw the line where these workarounds are used INSTEAD OF real world procedures (at least, those RW procedures which can work in VATSIM) like not using Unicom, for example.
if they aren’t participating, they should be ignored. just as if they just spawned in and parked on a runway.
I don’t say anything, really. You said you “hate flying on Vatsim when there’s no ATC online.”. I asked what I therefore think is a logical question. This is a game, it’s for entertainment. By its very definition, you really should enjoy it. If you don’t… If you actually hate it… Why do it?
It would seem much easier (and more reasonable) to simply disconnect, than to try to get the entire organization to change their policies just to suit you, right?
Monitoring unicom, and using it when applicable, is simply part of being on the network without ATC. If a person can’t devote the necessary (and miniscule) amount of attention necessary to do this… What’s the point of being on the network? You aren’t paying any attention to it anyway?
Good point, it was just bad English on my part. By “use” I meant “transmit/announce”. As per our rules you always need to be tuned to 122.800 unless you are inside active airspace.
Can’t get any clearer than that.
Ok, I give up. Seems like I can’t express properly what I try to say. 
How “far” does Unicom reach in vatsim? If I’m announcing on Unicom in Washington, is someone flying between Hawaii and Japan going to hear me or does it limit to the airspace you are in, even if, for example, there is no active ATC in at Seattle Center.
Text on 122.800 has a very high range, depending on your height above ground.
Voice on 122.800 has a range of exactly 15 NM. This means anyone who is farer away than 30 NM from you cannot hear you.
Except in Australia where it seems to have a range of hundreds of miles.
That’s interesting. At least according to https://afv-map.vatsim.net/ even in Australia everyone on 122.800 only is showing a 15 NM voice range.
I can assure you that pilots in Australia are hearing UNICOM transmissions from 300-400 nm away, sometimes more, for many months.
i thought it was 15+15nm = 30nm
ie. if your 15nm circle touches another persons 15nm circle you can hear each other
I thought so, too, and that’s how it works (outside Australia 
)
UNICOM is VHF, and is therefore line of sight. Maybe VATSIM arfificially reduces the range, and if so, that restriction doesn’t work in Australia for some reason.
Yes, that’s how it works: the voice range of this specific frequency (122.800) is controlled through server and has an artificial limit of 15NM from each station that is tuned to it, no matter at what height above the ground they are.