> CD's scratch and then skip easily
You can back up a CD's audio tracks digitally to PCM files, with no loss. You still have the music even if the CD is completely destroyed, and your backup survives.
Vinyl records are also sensitive. They can skip even with slight vibration, because the arm which holds the needle is delicately balanced to exert only a small force to keep the needle in the groove.
Vinyl records easily warp from heat. They still play, but the warps make it easier for skipping to occur.
Fun personal fact: my grandma hard a way to make records flat again. She sandwiched them between cotton cloths, and gave them an ironing!
> Skipping to a certain part of a song is much more difficult with CD's.
Skipping to a certain part of a song is very difficult with a vinyl record. The song consists of a strip of grooves that are only a couple of centimeters wide. The resolution for navigating is not very good. Even if you could pick a specific cycle of the groove, which you won't, your precision is still limited by the rotating latency. At 33 rpm (let's round off to 30 rpm), you have one revolution every two seconds. (Sure, you could stop the rotation, and fiddle with it for five minutes to get the exact spot in a four minute song.)
With a CD-ROM drive and PC/laptop, you can script up some software to seek to a position with sub-second precision.
A decent media player lets you mark off two points, A and B, with sub-second precision, and loop them.
A bookmarking feature is plausible; there is no reason why a CD playing application wouldn't let you make bookmarks associated with CD's. Pop in a CD, and see a list of bookmarks; pick one and there you are at your favorite part of a favorite song. (If this doesn't exist, propose it ... say for VLC, or hack it yourself.)