Is there any reason to move away from fstab on a systemd system?

From man systemd.mount itself:

fstab

Mount units may either be configured via unit files, or via /etc/fstab (see fstab(5) for details). Mounts listed in /etc/fstab will be converted into native units dynamically at boot and when the configuration of the system manager is reloaded. In general, configuring mount points through /etc/fstab is the preferred approach. See systemd-fstab-generator(8) for details about the conversion.

Note that certain features are only implemented for fstab. For example when systemd in the initrd is used to mount the /usr filesystem as well as the / filesystem. systemd in the initrd reads etc/fstab on / and looks for an entry for /usr.

It also lets you use mount /mountpoint manually. systemd is generally happy for you to do this, e.g. it will update the status of the mount unit when you unmount or mount the filesystem.

systemd mountpoints support more flexible configuration of at least when to mount each point. That's sometimes useful in really complicated problems with network mounts etc.

As a rule of thumb, you just use fstab unless you're stuck with configuring some complex behaviour (if you ever do), then try to find systemd solution.