That is certainly not the case, either something unexpected happened or either of you didn’t have the families beta on. I have never logged in someone else’s PC and neither have someone logged on mine, I always use Steam on beta and I was able to send family invites to my friends, however only the ones in my region (country) were able to join.
In the real world with real people, what matters is efficiency. Top performance that you can only achieve in benchmarks is not any indicative of efficiency.