Value, respect, and strive for diversity in editors
I think both of your theories are correct. As always, we need to find the right balance, and I commented because in the current document I could see only one side (Theory 1). On the other hand there are people like the guy who appeared on the English Wikipedia and seemed unable to form a single short English sentence. Instead he kept spamming people with excessively long sonnets that (so far as I know) nobody could understand -- although some of the words he used suggested that the sonnets were custom-built and somehow related with the questions he had been asked -- and very long, confused paragraphs full of eccentric formatting.
That kind of thing can disrupt an article completely if it takes too long for the community to agree that such a user needs to be banned for using up much more of productive editors' time than he is worth. And a lot of people, especially experts, are simply not prepared to work in such an environment.
At the German Wikipedia it's relatively normal to block people with the reason "no discernible intent for encyclopedic collaboration". For the English Wikipedia this is an unacceptable reason unless a user is actually vandalising.
You say "At the German Wikipedia it's relatively normal to block people with the reason "no discernible intent for encyclopedic collaboration". For the English Wikipedia this is an unacceptable reason unless a user is actually vandalising." This seems to be a cultural difference. It is doubtful such a no-nonsense approach would be generally supported on the English Wikipedia. If nothing else, it involves jumping to conclusions rather quickly. People often play around a bit before they get down to work. Assume good faith is a sound approach.