Comment by Lt_Riza_Hawkeye

They need to, as when the "." is not present, your search domains are used, but they are not used when the trailing "." is present.

For example, if you enter "ajdfajkhdfkajd.com", and your search domains contain one item called "mycompany.tld", then the browser will first query DNS servers for "ajdfajkhdfkajd.com.", and when an NXDOMAIN is returned, they will try "ajdfajkhdfkajd.com.mycompany.tld." next. If you type "ajdfajkhdfkajd.com." in the browser directly, only the first query is attempted.