What does Computer Hope's dictionary mean when...?

[Vigaenson]

...explaining at http://www.computerhope.com/jargon/b/bbc.htm what a BBCode is, says it enables users an easy way to format their text on a forum or bulletin board without having to compromise the stability by allowing users to insert HTML code?
In this context what does compromise the stability mean ?

[Broni]

A malicious code may be inserted into HTML script, while it's impossible to do the same with BBCode.

[Vigaenson]

Hi Broni
Thank you for your reply
It seems I had forgotten my manners.
Vigaenson

[Broni]

You're very welcome