I see ways they can be competitive without taking the route of cutting Carr, but most importantly Moore and Loomis both see the team as being able to compete this year, so they obviously see something that some here aren't able to see. It makes sense, since they have a lot more information and details than anyone here.
There's more than one to go through those steps. There's a whole bunch of options at each step. The team can get better while also keeping Carr as the starter for a couple of years, until they find a better QB. The Saints don't have to cut Carr to get better or for Moore to find his long term QB.