I think there're some good and positive reasons including:
1. If I'm going for a full stack interview soon, having a quick look/update would provide a good refresh before digging in deeper.
2. Someone wants to compare between different aspects/features of different languages, some quick learning would definitely provide a good sense of differences.
Most jobs forces people to do things as quickly as possible, and that results in trying to learn things quickly. I see nothing wrong as this is being part of adapting to the environment.
1. If I'm going for a full stack interview soon, having a quick look/update would provide a good refresh before digging in deeper.
2. Someone wants to compare between different aspects/features of different languages, some quick learning would definitely provide a good sense of differences.
Most jobs forces people to do things as quickly as possible, and that results in trying to learn things quickly. I see nothing wrong as this is being part of adapting to the environment.