The problem in Chicago absolutely was, at the very least, exacerbated by not enough chargers.
How? Teslas preheat their batteries when you're headed to a charging station, so that when you arrive, the battery is warm and can take a normal charge rate.
What happens when too many cars arrive there at once? They have to wait, the battery stops warming, cools off, and now it takes longer to get the charge speeds ramped up, causing a domino effect of delays.
The problem is also made worse when there are people who don't navigate to the charging station (like people who don't have home charging and just drive to the one they know). Their battery is not pre-heated and it causes a delay, which causes other cars to be delayed, their batteries to get colder, etc. Domino effect of not enough chargers combined with people not knowing how to use their car correctly (pre-heat battery), and the car not realizing it should still keep the battery heated when waiting in line (which also may stop if the range gets low enough to not strand the driver).
So, yes, more chargers would have absolutely greatly improved the issue.
The other evidence that this is true is that this issue wasn't widely reported in other similarly-cold areas. If it was as simple as "cold = charge slow and dead Teslas" there would have been similar incidents all over the Northern states. But when traffic is lighter to Superchargers, the batteries are often pre-heated and get in and out quickly, not causing backups that worsen the problem.
This isn't to say cold weather isn't an issue at all, but more chargers will help and more experience will help, and probably some software/hardware changes to the EVs themselves.