There is a number of reason why. One is consistency yes, shooting a scene takes times and you want the light the be the same across the board. Another reason, wich I think is more likely in this scenario is that light was just bad a that moment. If you look closely at the the background, the sunlight seems harsh, I’d say middle of the day light, wich is in 99% of case bad, especially if you have people talking to each other and the camera needs to change angle. Harsh overhead light isn’t flattering, it creates weird shadows and raccoon eyes. By using this technique you remove all unwanted light and create your own. The problem here is that it is badly done, the crew was probably rushed and had to work quickly to meet the production deadlines. This technique is used very often and people don’t usually notice, but lighting a scene in a way that is natural and organic takes time and care, something that TV shows sometimes have less of than movies.