And maybe they are right: I understand that not all new contributions are valuable to the project (though you could argue that improving upon them is better than outright deleting them — obvious spam and vandalism excepted ofcourse). But you can't have it both ways: either you want to invite new contributors, in which case you need to be tolerant of their mistakes, and ensure that they are mentored instead of bullied by the more experienced users, or you choose to have a small group of trusted veterans maintain all articles. I don't think one option is obviously superior to the other, but it's a choice that Wikipedia doesn't seem to want to make.
There is lots of room for improvement here. For example, I get the impression that Deletionists now rule Wikipedia, so if a newbie like me tries to create a new article on any topic, there is a 90% chance it will just be deleted (because if the topic was worthy of an article on Wikipedia, don't you think someone more experienced had already created it by now, silly noob?)
If that's the case, then why allow people to create new articles at all? It's just setting up people to waste their time creating an initial draft. And it's an annoying gamble: I know that the more time I spend on making the initial revision really really good, the less likely it will be insta-deleted by some grumpy guy, but the more time I will have lost if it is! It's a real dilemma. Why make people gamble with their time like that?
If you accept that most new articles will not be accepted, wouldn't it be better to disable article creation, and instead have a form where people can suggest ideas for new articles? That way, you spare contributors the effort of creating the initial draft (which is actually really difficult if you're new to Wikipedia and you are trying to be diligent about creating properly-formatted references and info-boxes and so on), and on the off-chance that the people in power decide to allow the new article to be created, they could also pair up the new contributor with a more experienced editor who will mentor them and help them create an initial revision that's up to snuff. This strikes me as a process that's 1000% better if you want to encourage new contributions.