How far down the stack does that requirement go, though? Anybody who knows what a userscript is will know why they need a userscript manager and anybody who doesn't won't need one.
The homepages for Firefox and Chrome don't explain what a browser does, nor what the WWW is, or a webpage, etc, etc
I don't agree with your statement that "anybody who doesn't [know what a userscript is] won't need one". If it was explained better there might definitely be people who could use this and become interested in this, without knowing its name before.
This might be the first time some people hears about userscripts. It is certainly possible to have been an internet user for many years without hearing about them. Does not mean they would not be useful to a subset of such persons.
