Yep, even the core playlists of TDM and DOM on the likes of Infinite Warfare struggled to get games going on DLC maps because of the low content sales and existing population. People were buying the new maps and not even being able to play on them especially when they were injected into the main rotation.
Back when you had 750,000-1m online at a time, you didn't have to worry and could easily get a game going on any map and any mode at any time but now what's left of the player base is split more than ever with low amount of players, DLC owners and then you have the SBMM also stifling the chances.
Free maps is sensible and long overdue.