The only relevant fact is that it was consequentially better for the administrator to behave otherwise. Even if we assume that the user was 100% in error and that the pages should be removed, the administrator's actions still served to objectively harm Wikipedia (in net).
Off the small fraction of people who do try to do this, most will probably think, "I guess I was out of line, since Wikipedia is an encyclopedia, not my personal storage space." Anyone left over who is going to ragequit over someone not being nice enough when they enforce the rules, frankly, probably doesn't have the type of personality that can handle a lot of the often heated discussions that go on on Wikipedia.
Honestly, I imagine the extreme edge cases represented by the productive editors likely to be seriously dissuaded by this are not a real contributing factor in any perceived death or decline of Wikipedia (one of the most successful and widely used products on the internet).