Hey Stephen,
There is a big understanding of this issue and is mainly related to the fact that the users are new to joomla and doesn't understand how it works
Here is my explanation - you don't have to pay me for this, but if you wish you are welcome
There are 3 ways to control the read more button in joomla.
1st - article manager ->settings -> here you can choose if the read more should be generally turned on or not.
2nd -> on meny level- > you can choose for your frontpage entry or blog entry if it is allowed to show the read more button.
and 3rd -> when you write the article on the right you have an option to show or hide the read more or not.
So here is the importance of this settings:
1st: article manager settings
2nd: menu entry settings
3rd - article settings.
Basicly what the option "if Read ON set in menu" tells you is that - when you have set the read on button to show in menu settings, then you will also see the read more button.
what I think that you've done is:
on your blog menu entry -> you've choosen in the settings to show the read more button.
but on your frontpage menu entry -> you've set this option to hide the read more button and that is why you don't see the write comment button.
Do you understand it now?