I don't think it's gatekeeping. I think it's because experts need different tools to beginners, and have louder voices when a tool doesn't meet their needs.
Consider Ruby on Rails. It was the most beginner-friendly way to create a web app when it was popular, but the very things that made it that way - opinionated design, sacrificing speed/correctness/scale by using Ruby, "batteries included", and a cultish fanbase that drew new users to it - made it the target of justified criticism from experts who wanted flexibility, type safety, speed, lightweight design, fewer CVEs, and fewer annoying fanboys. Flash came under fire for similar things: performance issues, poor UX when used in the wrong place, constant security vulnerabilities, being a proprietary standard.
These are actually good criticisms! There's no shadowy cabal who arranged feigned outrage over flash vulnerabilities, people were genuinely upset that a proprietary piece of software was turning their browser security into a sieve and stopping screenreaders from working. The criticisms just failed to ask why it was so popular with beginners anyway.
I agree with much of what you say, but I disagree that RoR was "beginner friendly". It had/has a steep learning curve.
From personal experience, and from the (continuing) weekly HN "Hiring" posts that are looking for Rails devs, Rails is popular because it allows you to build an MVP for an entire product or company over a week. It gets rid of all the distractions when it comes to assembling the perfect stack and just works. It's not perfect by far, but, like Flash, it allows you to shortcut the technical work and get right to the creative work.
Consider Ruby on Rails. It was the most beginner-friendly way to create a web app when it was popular, but the very things that made it that way - opinionated design, sacrificing speed/correctness/scale by using Ruby, "batteries included", and a cultish fanbase that drew new users to it - made it the target of justified criticism from experts who wanted flexibility, type safety, speed, lightweight design, fewer CVEs, and fewer annoying fanboys. Flash came under fire for similar things: performance issues, poor UX when used in the wrong place, constant security vulnerabilities, being a proprietary standard.
These are actually good criticisms! There's no shadowy cabal who arranged feigned outrage over flash vulnerabilities, people were genuinely upset that a proprietary piece of software was turning their browser security into a sieve and stopping screenreaders from working. The criticisms just failed to ask why it was so popular with beginners anyway.