As if there have never been first corner pileups in Indycar racing.
At Indy itself though, it helps that they start with the rows further apart than normal, and it helps massively that they don't have to brake for the first corner. That's when first corner pileups happen, because the entire field is slowing for the first corner and people misjudge things.
Cut the crap about "best drivers in the world". Getting 20+ cars, accelerating from a standing start and all arriving at the first corner at the same time with different braking points is going to lead to a lot more chaos than a similarly large field approaching a corner where they're all approaching at the same sort of speed and don't have to slow down. Part of the reason why rolling starts are usually considered safer is because everyone is already rolling, the gaps tend to be bigger and everyone is approaching turn 1 at a similar speed. With a standing start, the guys who started at the back are approaching the first corner faster than those who started at the front.
You only have to look at what sort of circuits produce first corner pileups. Places like Spa and Monaco. Places where the first turn is very tight and or street circuits. First lap incidents were quite rare at Silverstone when Copse was the first corner and the first heaving breaking was halfway round the lap at the Vale. Now while most tend to get through Abbey and Farm without problems, things get crazy at Village.
Honestly, if there's one place you wouldn't expect a lot of first corner crashes, it's the big ovals.
Going back to that 1996 US 500, the start grid crash was one of the most unlucky events to happen in and around the split. It gave the CART detractors an wholly unfair stick to beat the series with, because they had no problem doing 3-wide starts at Michigan in previous years and managed it without problems in the Marlboro 500 that year.