It’s certainly not perfect, but I would definitely not class it as useless in many circumstances

Asking it to do a summary on a paper or meeting notes I’m mot familiar with, yes the utility is very limited exactly the way you’ve pointed out.

However, asking it to summarise or shorten a paper or meeting notes I’ve been directly involved in - that has enormous utility for me.

It provides me a quick starting point to create summaries, and I get to see if the salient points are addressed, and if not, I get to add them in.

I’m no a fast writer, and often experience writers block, so having a fast way to start is enourmously useful to me.