Live chess does has a minimum and maximum rating box.
Setting limits of challenger rating

You used to be able to but the min rating and max rating options for me both dissappeared for live chess a couple of weeks back.

It's hidden. Choose custom and a rating option button pops up. Could take much longer to get a match though. You should probably read this:
https://support.chess.com/customer/portal/articles/1622811-how-are-seeks-matched-in-live-chess-
and this:
http://www.chess.com/forum/view/livechess/new-logic-for-auto-pairing-and-seek-graph
One can set a min and max rating of potential challengers for long term chess and other items but NOT for "live chess." Why is that?