Most recently, a github user opened a issue on one of my projects and asked "Why should I use this instead of Y".
As a developer sharing my code online, I don't even know where to begin answering that.
This is typical non-tech spam.
If I'm writing FOSS and someone asked me that, I'd just reply with ¯\_(ツ)_/¯
I'm not making money from it, so trying to convince some random individual to use it is a waste of my time. Sure, I'll describe the features in the README and possibly include comparisons to other software, but I won't go out of my way to convince a specific rando just because they asked.
No this is a valid request.
If a user wants to use a piece of software to do A and several different pieces of code do that - why should they choose yours.
What is your selling point.
Especially if they have been using the other product why should they switch to yours?