What are the benefits of copywriting services?

Copywriting services write text for you that meets your specifications, is grammatically correct, and is clearly written. Is that what you want?

Or do you want copyrighting services, where some business entity applies for the copyright to your work on your behalf? IMO, that's a complete waste of money.

For the bozo who says it has anything to do with protecting an invention or ideas, the COPYRIGHT laws (in the USA) specifically exclude those rights as they are not part of the copyright.  You cannot copyright facts or inventions at all.  17 USC s.102(b).  However, the question is NOT about copyright but rather copywriting.

To protect your invention from being stolen. To give you sole usage of your idea for a certain amount of time before others have permission to copy your invention or make cheaper generic alternatives with out your permission.

You get well-written, correctly spelled, correctly punctuated copy which looks professional and is easy to understand.