I never said they were problematic, I just don't prefer them for friendships. Maybe the difference in quadra provides something new, something more novel for friendships.
As for the quasi-identicals, again this is the context of friendships, we bond over same interests, namely writing and reading. I've never had romantic experiences with quasi-identicals, so I don't use the word 'love' in that particular sense.
Imo, it's more likely for people to be friends with people from other quadras than not, we're not all confined to one quadra. How would society function if we only got along with our quadra mates?