A rating is still an estimate, not a guarantee of equal skill. New accounts are especially uncertain: everyone starts at 1500, which doesn’t mean everyone plays at that level. The preview identifies opponents with no completed Duels as having a new rating.
That's the risk for new players because there are no build-up games for assessment of a player's rating, you could be up against a newly registered player with a higher ELO than yours.
I don't know about their assessment rating, if it's on a standard that is applied, like on the World Chess Body, FIDE uses a mathematical formula to rate their players, a win does not guarantee a high rating.
