The sentence like it is shown is in general okay, as it is neutral and does not prefer any user or answer and doesn't say anything about points.
And in the context mentioned above (OP had himself written that the issue is closed) it is okay too.
But honestly, if he had not closed the discussion, then he probably did not know how to do it. In that case such sentence would not not really guide him
However, if you add this as a reply to any content where you participated and which did not get closed immediately then it gets already a smell.
And if it gives an example to all others then we have a lot noise and 70 % of all discussions would end with a reply having this statement.
I prefer that a moderator is approaching the member, a moderator can do this "silent" with a direct message, can even add a link to my blog to guide the user. I do this regularly when I see users who have more than 5 or 10 "open" questions with numerous answers. Especially when I see that this user always closed his discussions before the new forum was implemented and suddenly stopped doing it.