Let suppose an unrated player plays a FIDE rated swiss tournament where its opponent's ratings are e.g. 1300,2000,2100,2200,2300 and wins all of them, then his initial rating will be 2100 according to FIDE rating calculator and FIDE documentation confirms this:
If he scores more than 50%, then Ru = Ra + 20 for each half point scored over 50%
Here Ru is the (new) rating of the unrated player and Ra is the average rating of the rated opponents.
Clearly, this player performed much better than the calculated rating (any performance calculator admits that). And I believe many before me have seen such an issue and such a performance (or maybe slightly weaker than that) from an unrated player is not impossible since many just don't play rated games. I'm wondering what is the rationale behind this? Does it mean that FIDE wants players to play enough many games before they win any title? Or is there any other reason to not use performance for calculating the rating? Were there already some discussions about the initial rating calculation?