SO could have been a place where someone could post a question, and a decent search algorithm could offer answers from previously answered questions; if it was a unique question then it could be opened to answers. Instead, SO decided you needed to earn the privilege of posting a question by answering questions posed by others. That right off the bat excludes a ton of people who don't have the time to wait for a question in their domain, and answer it before 1000 other people.

Sure, it's the Eternal September for tech sites. Comes with the territory. If you don't want people to visit your site (and contribute moderation and content for free), be hostile to new users. Reward aggressive closing of questions. Sure is a good way to drive away anyone but the most pedantic control freaks.

I used to refer people to SO when they would come to me with a question I couldn't answer, (I even have an SO t-shirt hanging in my closet) but now I'd only do that to my worst enemies.

This is false. You can post both questions and answers without any rep.

How people get the basics of SO wrong and still have such a strong opinion on how it works baffles me all the time.

It already does that, though. The current iteration of the 'Ask question' page finishes with box proposing existing questions

And yet, the site died exactly because of that ...

SO's toxic moderation isn't strict.

strict /strɪkt/ adjective demanding that rules concerning behaviour are obeyed and observed.

Proper moderation for rules can be no more strict than are the rules themselves, and SO's are appallingly slack.

E.g. try and find the rule prohibiting duplicates. Mods have fabricated their own definition: "Questions may be duplicates if they have the same (potential) answers" (verbatim).

Using that bogus grounds to close a question that fully follows the delared rules is, yes, toxic.