That's right. To stop overcrowding rather than trouble, mind.
And I've definitely been to sports events where I've been asked to show a ticket to get anywhere near the stadium. Typically, to avoid people without tickets milling around.
When buying tickets for a World Cup match, the purchaser...
You couldn't get into the Olympic Park without a ticket. You had to show it again to get into a stadium.
On some days (eg final Saturday) you could even go to the Westfield Shopping Centre without showing your Olympic ticket.
Regardless of whether you agree with the slightly unusual rules, or whether you actually qualify for the ticket, surely you're not arguing that there will be MORE trouble because of this?
More MOANING on messageboards and a slight inconvenience for those attending, maybe, but not more trouble.