That's common practice. I've heard of several occasions where "orienteers" from obscure countries have entered a major event to get a formal invitation to present when applying for visas.
I think both WOC and WUOC have experienced this.
Common practice it may be, but the poor Azeri organisers didn’t know (and neither did I) and they spent ages trying to get them a visa - which in the end they managed but too late! It’s only valid for Azerbaijan and Russia but that may be good enough for them if they want to go eg to Moscow.
The IOF should really send a note to all federations about it, I’ll ask them.