If you never reject or accept meetings, a colleague can never know if a booked slot in your calendar is something you intend to attend or just something you don't care about but didn't reject. So your availability in your calendar is meaningless.
I have colleagues that permanently have their entire calendar booked, even if they attend only half of it. So either you send them an invitation regardless of their availability, call them to check, or leave them out of the loop entirely.
Why would you invite someone to a meeting if you don’t expect them to attend?
At least that’s how it works in our company, so if you’re invited you are expected to attend (and be unavailable) unless you explicitly reject the meeting (which I don’t think anyone but me ever does).
There are all sorts of “meetings” that are optional- largish seminars/brown bags/trainings, meetings sent to multiple members of a partner team with the expectation that only one representative attend, social events, etc.
I’m not sure you are indicating that people or shouldn’t explicitly accept or decline invites, but I’m definitely in the “keep your calendar accurate” camp (although my orgs cultural expectation is that “tentative = free”)
It defaults to tentative if you’re not accepting the invitations. So yeah they’ll try to double book you because you get to tentative by either being listed as optional on the other invitation or being non-committal.
Also the organizer of the original invitation never heard back from you so they don’t know wtf ur doing.
Accepting/rejecting may not be valuable to you, but it’s a courtesy and a time-saving tool for organizers.
You know your own workflow better than any of us.. but I'd also be willing to wager that you're losing minutes responding to inquiries about your true availability in return for not losing seconds clicking "accept" or "decline" on meeting invites.