It's not a new product. The functionality I'm talking about dates from when Apple Music was iTunes.
You can listen to the playlist offline just fine. I just mean you can't export a playlist of trimmed tracks as audio (e.g. "My Mixtape.m4a") from within Apple Music. If you sometimes want to hear the full track and sometimes want to hear the trimmed tracks as a mixtape, then it's not a good solution. But if you just want to cut a 5 minute intro or 20 minutes of "hidden track" silence then it's there.
You can listen to the playlist offline just fine. I just mean you can't export a playlist of trimmed tracks as audio (e.g. "My Mixtape.m4a") from within Apple Music. If you sometimes want to hear the full track and sometimes want to hear the trimmed tracks as a mixtape, then it's not a good solution. But if you just want to cut a 5 minute intro or 20 minutes of "hidden track" silence then it's there.