Wifi is often deployed at large events (PAX East for example) and it is more then feasible if the company is willing to pay the money for another company to do it.
However, their server infrastructure is another question entirely. In today's age, making scale-able network services with very little downtime is not something that requires a dedicated networking team and hundreds of millions of dollars. I can't imagine they have very many good excuses to why they continue to allow this to happen other than that they don't value investment into their infrastructure enough (despite being a company completely dependent on the internet)
The problems that they are experiencing are ones that have caused problems and had solutions created for them for years. The just seem to be unwilling to properly invest in the solutions to fix them, which are cheaper than ever (considering the complexity of the issues in the grand scheme of things).
[0] https://tradeshowinternet.com/solutions/event-organizers