No, it's not. In a real backup solution (Time Machine, borg, restic), if a file exists at the time of the backup, it will be included in that snapshot, even if snapshots in between are removed.
With ZFS snapshots, only blocks changed since the previous snapshot are included.
The term "incremental" backup (in contrast to "full" backup) is no longer as useful as it was in the 2000s -- GP is actually correct that "incremental" backup systems don't provide this feature (since incremental backups only include the difference from the previous backup).
However modern (or, if you prefer, "real") backup systems backup systems" (like borgbackup and restic) aren't "incremental" in this traditional sense, they are a mix of both "full" and "incremental" backups such that you get the benefits of both without the corresponding downsides.
Right, but my point is that "traditional" views of backups had two types of backup -- incremental and full. The "let's store the delta between snapshots" solution is what would traditionally be called an "incremental" backup while a full copy of the entire filesystem would be a "full" backup.
Time Machine might call itself an incremental backup, but this just leads to more confusion -- it's a next-gen backup system (that has the benefits of both the "incremental" and "full" approaches) just like restic, borg-backup and all other similar projects.
With ZFS snapshots, only blocks changed since the previous snapshot are included.