This is pure speculation, but I imagine there are plenty of people that could write a passable show, and would even do it for free if given the opportunity. Same with other art. What leverage do these writers actually have?
Yes, anyone can write a passable show just like anyone can write compilable code.
I encourage you to enroll in a screenwriting class if you don't believe me. You'll understand soon enough. :)
And I'll go a step further and seize on the word "passable". Would you rather watch a show that's simply good enough to "pass" as a show, or something of higher quality? Plenty of people can write something that you could pass off as a show, but I'd imagine that that number drops as you reach for something of a higher caliber.
As for quality, it's not clear to me that current shows/movies are even that good in terms of writing. If you are a truly talented writer that can make/break a work you should have similar leverage to a director or lead actor, but studios don't think you are and that's why you're in a union. Maybe if your buddies that are actually talented gave a creditable threat of committing career suicide that would be good leverage, but it doesn't seem like a real threat when top talent will always be paid well.
Passion "for the work", not necessarily simply writing a show itself. I'm talking about being in a writer's room with others for eight-plus hours a day, dealing with the opinions of others, being OK with having your ideas axed because some producer didn't like it for whatever reason, the process of pitching ideas, and everything else the job entails.
Absolutely no implication that unions are loyal, no