It is actually extremely standard for pet and avatar websites to compensate staff with the equivalent amount of premium currency instead of real money, sometimes with the promise of switching everyone over to real money once more profits are flowing in, but sometimes no options or suggestions of a real money option at all. As dour as it sounds the fact that one has a choice is better than other VPS I've seen.
Ideally like this wouldn't be a thing and I wouldn't be so immune to seeing this to the point where im like "oh wow the OPTION of getting paid real currency? hot dog!" but its a symptom of the genre... However forums like VPL and TGL have done wonders in helping push a shift to artists, writers, and coders getting paid on petsites specifically by having a community where everyone can showcase their work and rates. Though many petsites remain passion projects with little to no startup money so I'm not sure if this style of more pro-bono or voucher based work will ever truly go away.
Oh, and, also while this is more of a niche situation but some countries are a bit iffy with paypal or other similar websites, so paying via premium site currency can be the only option for some ppl. But that's more of a fun fact than anything.