How many weeks/months can they use this excuse? They are literally are at the forefront of this emerging industry and are capturing untold value. To let their product suffer and potentially lose market share because of it is extremely foolish
At most normal companies you monitor your systems and address potential bottlenecks before they reach a tipping point. And generally you want enough headroom that a sudden 2-3x increase in demand wouldn't take out the service.
Either Github's technical leadership/talent is completely out of their depth (seems unlikely), or they're not hiring enough engineers to work on these capacity issues.
Regarding their leadership, I'd argue the latter implies the former.
So yeah I'd say they're out of their depth.