That employee's first responsibilities are to the venue and probably other events that are taking place in the case of a hotel. There's a good chance that they are also responsible for sales which take place any day of the week. While that person might be checking in periodically, they will not be there for the entire wedding and reception. It's more likely that someone will have to search for them if an issue arises.
This is one of the reasons why couples don't hire a Wedding Planner. They think that they already have someone to take care of them and any unexpected problems. You hope, but there are no guarantees that they will be there to direct vendors who are making deliveries. They won't be lining everyone up before walking down the aisle. That is what a Wedding Planner would be doing. The venue coordinator is there to take care of the basic foundations of the wedding by directing staff to do their jobs for your event.
To get more information about the assumptions about weddings that can result in headaches, you can read my book "Wedding Planning Unmasked!"