Only a surprise to noobs
This effect has been around since the beginning of time.
Whether it's hundreds of users coming in on a monday morning and all trying to access their email (off the one single server, that was only capacity-planned for a steady-state load) at the same time.
Or the hundreds of call centre staff who all go <click> when their shift starts: like the email or Windows servers "storm", but much more intense, as they all start within a few minutes of each other.
Or (worst of all) bringing up a system after a crash when EVERYone tries to log in continuously just as soon as they see the login screen.
It's even been a problem in the days of mainframes when everyone tried to fill in their weekly timesheets at 16:30 on a friday afternoon (they had to be done before you left, you couldn't fill them in earlier - 'cos you didn't know what you'd be doing - well you did: you'd be waiting for CROVM4 to respond for about 15 minutes)
But, of course, no manager is prepared to shell out for a system that's specc'd at 500% of their steady-state capacity requirements, to handle a workload that will only exist for a few minutes once or twice a week.