I don't think it's specifically that.
Mardi Gras is only one day a year but in NOLA, the "season" lasts for roughly a month.
The parade schedule, for instance, begins about a month ahead and really ramps up, the week leading into Fat Tuesday.
In addition to the parades, where a single krewe usually sponsors each one, those krewes (social clubs) also have all their own private events that go on at various points through the month and there is a ton of overlap there when it comes to resources and member involvement.
There are a lot of locals events that take place well outside the traveled tourist paths (and where tourists aren't particularly welcomed) that happen for that whole month, too.
It's basically just way too much to cram into a single day or even a single week even though many tourists only come for the final week or final couple of days of activity.