Not every feature is tied to Mojave. PowerPoint can make grammar and writing style suggestions on top of pointing out spelling errors. Word can embed fonts to preserve the look of your text across devices. And if you use Outlook for email, you can share your calendar, show multiple time zones, use Teams to connect to meetings, see meeting attendees and even prevent forwarding for meeting invitations. In short: this might be a vital upgrade even if you're not in a rush to adopt the latest macOS release.