He has 16 assists this season because he's playing with Haaland. Do you know how many assists he had last season? 8, just like Bruno does this season.
Bruno has the highest cumulative xAG in the league - more than de Bruyne.
If he had Haaland in front of him, he may well have had 15+ assists, based on Haaland's overperformance w/r/t to xG, and Bruno's outstanding xAG.
In fact, Bruno's xAG per 90 this season is almost double what it was last season (in the premier league).
Bruno has the highest number of big chances in the league, and the highest number of chances created in the league.
As for his ball retention? It is a completely valid point that de Bruyne loses the ball as much as Bruno does, given the fact that their creative abilities are very similar w/r/t to their statistical output. In fact, fbref shows that they are the two most similar players in terms of their statistical profile in the premier league.
And sorry, but de Bruyne has 73.3% pass completion percentage, which is lower than Bruno's - not 80.5%, so where are you getting that from?
That doesn't mean that Bruno is as good a player as de Bruyne is, but he certainly is comparable in this discussion especially when you're trying to invoke statistics as a means to rubbish comparisons with Bruno.