If you don't put it, then the function will not be able to compare access levels to the calling user, meaning anyone can call the command from console in-game..
Bad idea, unless it is a public command..
To compare access levels, we usually use 'cmd_access()' from amxmisc.inc:
Code:
public MyFunction( id, level, cid )
{
if( !cmd_access( id, level, cid, 0 ) ) // <-- 0 = # of Command-Line Arguments..
return PLUGIN_HANDLED
}