The version from 17.3 to 17.4 is mostly db optimization, and the devs said they'll be releasing v18 with major reworks any day now, so we decided to skip v17.4 and will jump to v18 the moment it's released.

You're probably looking for an official response, but using the email analogy, your version and email client itself doesn't affect you getting email from someone else with something different. Fediverse apps use a common protocol so they can share the core content with each other...how they display it may differ, and that's where what you use and how updated it is comes into play.