Even if your intent was to have most of your post in bold italic, there are still problems with your HTML. And leaving them in a post reminds me of a kid running off with his shoes untied, in his eagerness to play with his friends.
PerlMonks provides safeguards that I find helpful:
With those settings you will see the most common HTML errors identified when you hit preview. Then you will have plenty of opportunity to fix the mistakes before committing your document to public view. Even after it's been posted, you'll continue to see the nag-tags until you've taken the time to edit your post fixing HTML errors.
In that way, when someone suggests your HTML is broken you will not be unaware or unable to identify where it needs to be fixed.