There are a lot of distributions to choose from, and many of them are built on a foundation of one or another "LTS" system.
Some developers do this because they believe the "LTS" foundation does most of the work, so they don't have to. But that assumption might be broken. If everyone uses the LTS as a way to avoid doing the heavy lifting, then the heavy lifting doesn't actually get done, and you have a foundation that's mostly unmaintained.