I had to read your comment extra carefully to realize that you weren't saying LineageOS is _behind_ on updates for the baseband/etc., but rather that it only extends availability of Android updates, not baseband updates, due to the baseband being proprietary and updates no longer being released by the OEM.

In other words, LineageOS provides the latest Android and baseband updates available; it's just that for the baseband, "latest" can be a lot older than for Android, if your phone hardware is no longer supported by the OEM.