Maybe they didn’t explain everything that you wanted to know, but they were not replying to you. They were replying to OP.

OP wondered what Sticky Keys was for, not what it is. The comment answered that it is for anyone who might need it to operate a computer, while highlighting that the needs of that population are often forgotten or ignored.

If you want further clarification you are welcome to ask. You don’t have meet a perceived slight with further condescension.

it lets you mimic holding down multiple buttons at a time while only holding down 1 button. Its primary use case is for people who would struggle holding down multiple buttons at once, as the person you are responding to said.