Why F1 doesn't have drivers wait in their cars until instructed otherwise, I don't know. But while the race director should have moved faster, drivers should be respecting double yellow too.
It's nothing new; just a week or so ago I made another post saying that Charlie Whiting should have been held more to account for Bianchi's crash when he failed to put out a safety car despite having a car, marshals and a tractor in a critical location. It's all good and well saying drivers should slow, because while that's true, it's not a defined speed drop and most drivers will abuse it from amateur karting through to top level professional racing. Leclerc himself was angry on the radio that there was no safety car for exactly that reason.
Judging by their reaction when Red Bull radioed them, I think they were busy deciding whether to red flag due to the tyre failures. Not an excuse, as the immediate priority should have been the current danger on track, but they'd be wrong whatever they did imo
If you've got a car perpendicular to the track you should immediately throw a VSC to neutralise the race, then you can upgrade it to a SC or red flag as needed. There are no excuses for more than a few cars to pass through first and certainly not for a full 90 seconds to elapse.
Regarding Pirelli on first look I'm inclined to believe them. From the outside camera you could see Stroll had a massive hole in the tyre, which could have been caused by the spin, but then you probably would have seen the white kevlar belt, but it was just a massive gash, so I can quite believe it was a structural failure from something penetrating the tyre (not enough to cause a slow pressure loss, but enough for the belt to rupture at high speed).
As for Verstappen from the long view from turn one you can clearly see two pieces of debris bouncing along the track just before the tyre marks start to appear from the deflation.
We've seen what happens with Pirelli structural failures in Silverstone and Korea - they tended to rip the carcass of the tyre from the sidewalls and leave the track strewn with metal, composites and massive surface belts, but neither of these failures were anything like that.
As Pirelli themselves said, as I did I elsewhere at the time, you wouldn't expect the left-rear to fail - the right-rear is where all the energy and wear should have been.