Taking multiple rookies isn't the problem as much as taking projects, a group of Flagg/Harper + Lendeborg/Clifford + Kalkbrenner/Proctor isn't the same as another made of Ace Bailey/Fears + Newell/Essengue + Hugo Gonzalez/Hansen Yang. We just need to avoid multiple rookies in the latter category (like, say, Samanic, Primo, Blake Wesley, Hernandez, etc).
Multiple teams have done that with success, in 2021 New Orleans took Trey Murphy, Herb Jones and Jose Alvarado, while OKC took Giddey, Tre Mann, Jeremiah Robinson Earl and Aaron Wiggins; in 2022 OKC took Chet, Dieng, JDubb and Jaylin Williams. Imagine if those teams had said "we have too many rookies, let's take just one"? They would have missed on a lot of talent.
What the Spurs need to avoid is clogging the pipeline with projects that take their entire contract just to find out what you have and whether it's a viable NBA player, you should know in 2 years with 90%+ certainty whether you want to keep the player long term or not, and if not you just move on. But the draft is still a numbers game, and you need to take your chances even if you're good at it.