The issue is that once you open up the possibility of international attendance then you open a pandora's box. Already online I can see people trying to think of workarounds to be able to attend. The whole process of fan accreditation, which is troublesome every year, opens up the possibility of people saying they're 'accredited delegates' and 'working at the event' and using that as a genuine reason to travel. I'm sure the border authorities wouldn't be looking too closely at the different forms of accreditation. Also, you'll have those countries where either vaccination rates are low due to lack of vaccines or more worryingly the country has a very lax attitude to vaccinations and international travel i.e. Sweden. It all just adds up to the potential of a superspreader event, and I don't think I'm being melodramatic in thinking this.