I completely disagree.
If you visit most forums, you have a limited edit option. You can't just post a load of diatribe and then once you have stirred up a reaction, go back and wipe out whatever you said.
It's not a big topic. You are still free to say whatever you choose to post. You also have time to check grammer, spelling errors and so on.
I have introduced the limit for specific reasons. It will not be problem for the majority of users.
I can also increase the time limit if users don't think 10 minutes is enough to check / edit / comlete a post.
John