You've been downvoted but I completely agree. You cannot sanitize text for all possible situations; you can only escape it depending on the output format (database, html, etc).
These functions should be used to "validate" input rather than "filter" it.
I absolutely hate how for example phpBB creates garbled bbcode in the database because they thought that they should filter it or something, instead of doing it on output now every consumer of the data has to unfuck the content, because they messed up.
These functions should be used to "validate" input rather than "filter" it.