They CAN'T because you have to know that it exists to search for it on steam, then find it in the list...... There is no reference as FREE DLC ALPHA/BETA MAPS on the game store pages (RO2 or RS).
Nice idea for these packs, but nobody will use it because nobody know they exist, and also some people like me (using WINE) can not use steamcmd without logging in, and these server map packs must be downloaded as anonymous on steamcmd, another thing that will make these packs more unknown..
And another unfair thing is that who decide which community maps get included?? stopping the 'off topic'