Only in the first page of the newest questions there are 8 of the first 15 questions closed, and the numbers are not that different in the next pages. Couldn't this create a disincentive to generate new questions and decrease the capacity for dialogue?
If the questions weren't closed, the answers would all have to be deleted. We close questions that are likely to get a questionable response. I'm speaking from experience, maybe too much experience, but I can tell what kinds of questions are going to spark answers that are either just a series of Bible quotes or just some sort of anecdote. If any question meets the close criteria, we close the question. That's why we have close criteria.
It's up to the person asking the question to fix the question, which they rarely do. But when they do fix their question and find that they get better answers for it, they sometimes stick around and become productive members of the site.
It's not a bad thing, it means we have moderators who care about quality. If you see questions closed with no comments as to why the question was bad and how it can be improved, then we've got problems. But if OP's merely aren't taking advice, then they've got problems and we can't solve them through Q&A.
I have noticed a number of new users appearing over the past weeks and months, which I assume to be the result of national lockdowns in English speaking countries. Many of these will be unused to the site and may have found SE-C on random searches but may not have realised the constraints of the site and that it is neither a forum, nor a place of debate but is a platform designed to generate an archive of substantiated and referenced academic articles which can be searched as a resource.
The system is challenging to begin with until one understands how it operates and accepts the longterm advantages of how it does so operate.
Observation of how the platform works and perseverance within that given framework, I would suggest (from my own experience) is how to treat the system and how to, eventually, with appreciation, get value from it and how to, responsibly, with experience, give value back to it.
One of the biggest problems encountered by all Stacks is that new users either skim or totally ignore reading the Tour, Help Center pages, or review anything in Meta. Consequently, the new user comes to the site with an expectation of what it's about and how it behaves based solely on what the new user believes should be OK. And, of course, the new user always believes what they're asking is OK.
Probably the best example of this problem is that new users come to "Christianity" Stack Exchange and expect to find their flavor of Christianity, as if that's the only Christianity out there. It doesn't cross most of their minds that "Christianity" might refer to everyone who calls themselves a Christian, whether the new user agrees with that or not.
When I first starting using this Stack I chaffed at the rules because I, like the new users I just mentioned, did not take the time to understand the site before using it. Moderators like Peter and CuriousDanni slapped my hand (downvoted or closed my questions and/or answers) until I finally humbled myself a bit and started reading through the texts and participating on Meta.
It got better after that. I started participating as a member of the community rather than (to put it bluntly) an exploiter of the community.
While I respect JimG's comment, I believe it is possible to state generally that most questions are closed because the OP isn't following the rules. The rules exist to help encourage polite discourse, but they also exist to encourage site value.
Consequently, poorly written, badly formed, and argumentative questions are (and should be) closed. It's not just an action taken by the moderators — the community participates in this process. And it's not a condemnation, it's an opportunity for the OP to better understand the community and edit the question to become more valuable to current and future users of the Stack. Regrettably, few users look on closure as anything but a condemnation.